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CLASS-BOOK 


OF 

PHYSIOLOGY: 

J 

FOR THE USE OF 

SCHOOLS AND FAMILIES. 


COMPRISING 

THE STRUCTURE MD FUNCTIONS OF THE ORGANS OF MAN, 

Illustrated Sg 

COMPARATIVE REFERENCE TO THOSE OF INFERIOR ANIMALS. 


By B. N. COMINGS, M. D., 

U 1 3 

AUTHOR OF PRINCIPLES OF PHYSIOLOGY, PRESERVATION OF HEALTH, AND 
PROFESSOR OF PHYSIOLOGY, CHEMISTRY, AND NATURAL HIS¬ 
TORY IN CONNECTICUT NORMAL SCHOOL. 


WITH TWENTY-FOUR PLATES, AND NUMEROUS ENGRAVINGS ON WOOD, 
COMPRISING IN ALL ABOVE TWO HUNDRED FIGURES. 


SECOND EDITION, 


WITH AN APPENDIX. 

■» > 

1 > •> 

3 > 

NEW YORK: V , 

I). APPLETON AND COMPANY, 

443 & 445 BROADWAY. 


M.DCCC.LX. 



»wx/vssv'\ 


ENTERED, ACCORDING TO ACT OF CONGRESS, IN THE YEAR 1854, BY 

B. N. COMINGS, 

IN THE CLERK’S OFFICE OF THE DISTRICT COURT OF CONNECTICUT. 


V, 


% 

Transfer 

Engineers School U(W. 

June 29,1931 


PREFACE, 


The “ Principles of Physiology which has been so highly commended 
by all literary men, who have examined its merits, although well adapted 
to more advanced institutions, has been thought too large and expensive 
/ for the major portion of our schools. To meet the demand for a lower 
priced book, and comply with the desires of numerous friends of edu¬ 
cation, the Class-Book of Physiology is now offered to the public. 

The unanimous verdict of teachers in favor of the general plan of 
the “Principles of Physiology,” has induced the author to pursue the 
same method of illustration, and, if possible, bring to a higher perfection 
the original plan of that work. It has been his constant study in this 
treatise to explain and illustrate to the student, fully and clearly, as 
many of the most practical principles of Physiology, as could be 
included in the moderate limits of the present volume. 

That Human Physiology can be made more easy of comprehension— 
more profitable, and more attractive to the young, by appropriate refer¬ 
ences to the Comparative Physiology of the inferior animals, than by 
any other method—is an established fact in the mind of the author, 
though he m-ust leave it for others to judge of the success with which 
this plan has been developed. 

( Physiology owes much of its present eminence, as a deeply interest¬ 
ing and progressive science, to observations made on the structure and 
functions of the same organs in the lower orders of animals as are 
found to exist in man. Take from Human Physiology the light derived 
from Comparative Physiology, and it would become what it was centu¬ 
ries ago, an obscure and comparatively uninteresting science. 

The young universally feel a deep interest in the animated beings 
which they see around them. The horse, the ox, the dog, and birds and 
insects, are all objects of admiration and wonder to the philosophic 
mind of youth; and when they learn that each possesses organs 
approximating more or less in structure to their own, their sympathies 
are enlisted, they feel a deeper interest in their own organization, 
acquire more noble and exalted views of the position they occupy 
in the scale of being, and learn to appreciate more truly the evidences 
of an all-wise design in the works of their Creator. 







4 


PREFACE. 


Physiology cannot but be considered, by every intelligent and re¬ 
flecting mind, a deeply interesting and practically important study. 
It makes us acquainted with the structure and uses of the organs of 
life, and the laws by which they may be preserved in health and vigor. 
When a knowledge of the principles of Physiology shall be diffused 
through all classes of society, the sum-total of human happiness will 
be greatly increased, and more permanent enjoyment of health, and 
more exalted exercise of all the physical and intellectual powers, will 
be secured to each individual. 

This science has peculiar claims to the attention of every teacher 
who would be successful in his profession. It presents, in their 
true light, those facts which lie at the foundation of mental develop¬ 
ment, and suggests the best means of promoting intellectual growth. 

An appendix embracing various topics pertaining to health has 
been added to this edition, in the hope of making it of more practical 
value, and of greater interest to both teachers and pupils. 

F or the convenience of those who have not had sufficient expe¬ 
rience to dispense with questions, they have been put at the foot of 
each page, and at the close of the appendix; but there is left ample 
scope for teachers to propose many more. For those who may be ad¬ 
vanced in study, or who may review the book, a description of the 
figures and plates are recommended as a useful exercise. 

Carpenter, Roget, Wilson, Pereira, Bourgery, Aitken, Kirkes and 
Paget, Horner, Hassall, Agassiz, Wyman, Chambers, Griscom, and 
various other authors, have been consulted in the preparation of 
this work. 

The author is under obligations to the publisher of “ Principles of 
Physiology ” for permission to use the figures and such portions of tho 
text of that work as he found suited to his purpose. 


New Britain, July, 1864. 


CONTENTS 


PAGE 

INTRODUCTION,. 9 

CHARACTERISTICS OF ORGANIC AND INORGANIC MATTER,. 9 

DEFINITIONS,. 10 

CHAPTER I. 

CHARACTERISTICS OF PLANTS AND ANIMALS,. 15 

CHAPTER II. 

STRUCTURE AND COMPOSITION OF ANIMAL BODIES,._.. 19 

CHAPTER III. 

THE BLOOD,. 27 

CIRCULATION OF THE BLOOD,. 29 

CHAPTER IV. 

RESPIRATION,. 47 

• 

CHAPTER Y. 

ANIMAL HEAT,. 63 

CHAPTER YI. 

DIGESTION,. 67 

MASTICATION,. 67 

INSALIVATION,. 72 

CHAPTER VII. 

ABSORPTION,. 93 

CHAPTER VIII. 

NUTRITION,. 08 

CHAPTER IX. 

SECRETION,. W* 

CHAPTER X. 

THE SKIN, . . * l0C 





















6 


CONTENTS, 


CHAPTER XI. fj, 

THE NERVOUS SYSTEM,. -U* 

NERVOUS SYSTEM OF MAN,. 127 

SPINAL CORD,. 128 

MEDULLA OBLONGATA,. 131 

THE BRAIN,.,. 132 

FUNCTIONS OF THE CEREBELLUM,. 141 

FUNCTIONS OF THE CEREBRUM,. i42 

CONNEXION OF THE MIND WITH THE BODY,. 149 

CHAPTER XII. 

THE SENSES,. 53 

SENSE OF TOUCH,. 153 

SENSE OF TASTE,. 155 

SENSE OF SMELL,.- . 161 

SENSE OF HEARING,. 164 

SENSE OF SIGHT,. 170 

CHAPTER XIII. 

ANIMAL MOTION,. 192 

THE MUSCLES,. 2ig 

CHAPTER XIV. 

THE VOICE,. - 0 


THE HUMAN FORM, 


CHAPTER XV. 


243 


APPENDIX. 


THE AIR WE BREATHE, 

VENTILATION.... . 


QUESTIONS TO APPENDIX 


SYNOPSIS OF LAWS OF HEALTH 



































LIST OF 


FIGURES. 


FI 0 

PAGE 

FIG. PAGE 

1. Parent Cells, 

• 

20 

36. Single Gland of Small Intestine, . 

9Q 

2. Fasciculi and Fibres of Cellular Tissue 

,21 

37. Lymphatics, .... 

94 

"a. Areolar Tissue, .... 

• 

22 

38. Diagram of Mucous Membrane, 

95 

4. Corpuscles of Human Blood. 


28 

39. Appearance of Lymphatics, . 

96 

5. Dorsal Vessel of the Spider, . 

• 

30 

40. Section of Kidney, . . 

'J04 

6. Circulation in Crustacea, 


30 

41. Structure of Parotid Gland, . 

104 

7. Circulatiop in Fishes, 

• 

31 

42. Nervous System of Ascidia, 

121 

8. Circulation in Reptiles,. 


31 

43. Nervous System of Pecten, . 

122 

0. Circulation in Man, . 

• 

32 

44. Nervous System of an Insect, . 

123 

10. Diagram of the Pericardium, 


32 

45. Nervous System of Sphinx, . 

124 

11. Section of Right Side of the Heart, 

33 

46. Brain of a Cod—of a Shark, 

126 

12. Valves of a Vein, .... 


30 

47. Brain of a Bird, .... 

126 

13. Capillaries in a Frog’s Foot, 

• 

36 

48. Portion of Spinal Cord, 

129 

14. The Hydra,. 


48 

49. Skull of European, 

144 

15. Tho Serpula, .... 

• 

49 

50. Skull of Negro, .... 

144 

16. Respiratory Apparatus of Insect, . 


50 

51. Capricorn Beetle, .... 

153 

17. Interior of a Snail, . 

• 

51 

52. Vertical Section of the Nasal Cavity, 162 

18. Lungs of an Ostrich, 


52 

53. Bones of the Ear, .... 

167 

19. Air Cell,. 

• 

52 

54. Cavity of the Tympanum, . 

167 

20. The Larynx, Bronchial Tubes, &c. 


53 

55. Interior of the Eye, 

181 

21. Human Thorax, 

• 

54 

56. Section of the Eye, . 

181 

22. Development of Teeth,. 


69 

57. Refraction of Rays of Light, 

184 

23. Dental Capsule, 

• 

09 

58. Image on the Retina, 

189 

23’. Human Teeth, .... 


69 

59. Bones in the Foot and Leg of a Deer, 

213 

24. Section of a Human Tooth, 

• 

70 

60. The same of a Horse, 

213 

25. Jaw and Teeth of Rabbit, 


70 

61. Bones of the Arm,.... 

220 

26. Teeth of Herbivorous Animal, 

• 

71 

62. Bones and Muscles of the Humerus, 

oo<? 

27. Teeth of Carnivorous Animal, 


71 

63. Tail-Fin of a Whale, 

226 

28. Teeth of Insect-eating Animal, 

• 

71 

64. Kangaroos,. 

233 

29. Teeth of Frugivorous Animal, 


71 

65. Larynx of a species of L uck, 

235 

30. Teeth of a Rattle-Snake, . 

• 

71 

66. Larynx of a Rook, 

235 

31. Section of Mouth and Throat, 


73 

67. Vertical Section of the same, 

235 

32. Stomach of the Sheep, 

• 

76 

68. Human Larynx, viewed sideways, 

236 

33. Section of the Stomach, 


80 

69. Vertical Section of the Larynx, . 

236 

34. Mucous Membrane, . 

• 

81 

70. Front View of the Larynx, 

23G 

35. Tubular Follicle of the Stomach, . 


82 

71. Bird's-eye View of the Human do. 

237 






LIST OF PLATES 


PAQJ. 


ELATES 

4 I. Comparative View of the Organs of Circulation, . . 

\ II. General View of the Circulating Apparatus cf Man, . 

III. Organs of Circulation,. 

j IV. Organs of Circulation.—Heart and Lungs, . 

M > V. Organs of Respiration,. 

^ VI. Organs of Respiration, ....,♦• 

v VII. Organs of Digestion, . 

VIII. Organs of Digestion,. 

1 IX. The Skin, .... . 

X. The Skin,. 

1 XI. The Brain and Spinal Cord,. 

XII. The Nerves, .... ... 

' XIII. Organs of Sense,. 

L ' XIV. Organs of Vision.—The Eye,. 

XV. Organs of Vision.—The Eye,.j 

V XVI. Organs of Vision.—The Eye,. 

XVII. Organs of Motion.—The Bones.— Anterior View , 

1 XVIII. Organs of Motion.—The Bones.— Posterior View , 

r XIX. The Extremities,. 

' XX. Organs of Motion.—The Bones.— Comparative View , .. 

XXI. Organs of Motion.—The Muscles.— Lateral View , . 

XXII. Organs of Motion.—The Muscles.— Posterior View , . 

L XXIII. The Human Form, in various Positions,. 

t XXIV. The Human Form in various Positions, and Public School Play-grounds, 


13 

17 

25 

39 

45 

57 

77 

87 

109 

117 

139 

147 

159 

173 

179 

187 

195 

201 

209 
217 
22S 
231 

210 
249 


















CLASS-BOOK OF PHYSIOLOGY. 


INTRODUCTION. 

1. All bodies in which evidence of life has been 
observed, possess certain parts or organs, which are essen¬ 
tial to the existence of the individual. A plant or an 
animal exists bj means of its appropriate organs, and the 
matter of which they are composed is therefore called 
organized or organic matter. 

2. Minerals exhibit no signs of life, but they continue 
to exist without any distinction of parts or organs, and 
belong to the kingdom of unorganized or inorganic matter. 
A piece of quartz, for instance, may be broken into any 
number of fragments, each of which will retain all the 
characteristics of the original mass. 

3. Minerals may grow or increase in size by the super¬ 
addition of new particles to their surface; but they are not 
nourished, like organized beings, by interposing new par¬ 
ticles between those which already form their substance. 

4. In plants and animals, each part is essential to the 
completeness of the individual being, and no part or organ 
can maintain an independent existence. If a rose be cut 
from its stem, or an arm be amputated from the body, 
it immediately dies, and loses its original characteristics. 

5. A plant is dependent upon its roots and its leaves for 
vitality, and an animal cannot live without its heart, its 
lungs, and its stomach. 

What are essential to the existence of all living bodies'? What is the matter 
of which such bodies are composed called? What is the matter found in 
minerals called? Do minerals grow? How? Are they nourished? What 
is essential to the completeness of a plant or animal? Can any organ main¬ 
tain an independent existence? Upon what parts is a plant dependent for its 
vitality? Upon what parts is an animal dependent? 




10 


CLASS-BOOK OF PHYSIOLOGY. 


6. There are two conditions in which we may study or 
ganized matter: namely, as living beings and as dead bodies. 

7. The science of Physiology is derived from the first 
method, and the science of Anatomy from the second. 

8. Physiology makes us acquainted with the uses tc 
which the different parts are subservient, and the laws by 
which they are governed. 

9. Anatomy teaches the number, size, situation, form, 
texture, and composition of the various parts, with their 
relations to each other. 

10. Anatomy and Physiology, in their most extended use, 
apply to all organized beings, though they are naturally 
divided into the several branches of V egetable Anatomy 
and Physiology, and Animal Anatomy and Physiology. 

11. Animal Anatomy and Physiology are again divided 
into Comparative Anatomy and Physiology, and Human 
Anatomy and Physiology. 

12. Comparative Anatomy and Physiology are devoted 
to the lower orders of animals. 

13. Human Anatomy and Physiology are limited in 
their application to man. 

14. The divisions of Physiology into Comparative and 
Human are usually made as a matter of convenience in 
study, and not because the Physiology of man is peculiar 
to him alone: for the same organs which exist in man, 
may be found in greater or less perfection in nearly all the 
lower orders of organized beings. 

15. Comparative and Human Physiology naturally illus¬ 
trate each other, and thereby become more interesting and 
more easily comprehended. 


In what conditions may we study organized matter? What science is 
derived from the first, and what from the seoond method? With what does 
Physiology make us acquainted? What does Anatomy teach? How are 
Anatomy and Physiology naturally divided? How are animal Anatomy 
and Physiology divided? To what orders of animals are Comparative Anato¬ 
my and Physiology devoted? Why is Physiology divided into Comparative 
and Human? 






































































































































I 





















































PLATE I 


COMPARATIVE VIEW OF THE ORGANS OE CIRCULATION. 

Figure 1.- Circulation in the Insect.—a, The dorsal vessel, divided into valvulal 

partitions, by the successive contraction of which, the blood is propelled forward. I, by 
Canals which carry the blood to the head, c, c, Canals passing backward for the supply 
of the body, and returning the blood to the posterior end of the dorsal vessel.—The course 
of the circulation is indicated by the direction of the arrows. 

Figure 2.- Circulating Apparatus of the Lobster— In the lobster and crab, the heart 

nas but a single cavity, and the veins are indistinct, consisting merely of irregular channels 
excavated in the tissues, a, The heart; A, c, Arteries which go to the head and to the 
antenna or feelers; d, The hepatic artery, or artery of the liver; e, /, Arteries which sup¬ 
ply the thorax and abdomen.-After the blood has been propelled through these arteries 

by the heart, it passes into the great vein, g, g, from all parts of the body. Thence it 
passes to the gills, A, where it is exposed to the action of the air, and is then returned to 
the heart by the branchial veins, i, which correspond to the pulmonary veins of Man. 

Figure 3.- Sectional View of the Circulating Apparatus of the Lobster. — a, The heart. 

a, b , Venous sinuses, c, c, Branchial arteries, d, d, The gills or branchis?. e, e, Branchial 
veins, terminating in the heart. 

Figure 4.- Circulating Apparatus of Fish. —a, The auricle, having a single cavity 

to which the blood is sent from all parts of the body, b, The ventricle, which receives 
the blood from the auricle, and propels it to the arterial bulb, e, into the branchial artery, 
d. The branchial artery is sub-divided into the arteries of the gills, e, in which the blood 
is aerated. /, /, The dorsal artery, or aorta, which receives the aerated blood from the 
gills, and distributes it to all parts of the body, g, The vena cava, or great hollow vein, 
which conveys the blood back again to the auricle, A, Vena ports©, that branch of the 
vena cava which conveys the blood from the abdominal organs, i, The intestine. A, The 
kidneys. 

Figure 5.- Circulating Apparatus of Lizard. —a, Left auricle. A, Right auricle.— 

One of these receives the venous blood from the system, and the other receives the arte- 
rialized blood from the lungs, c, The single ventricle, which receives the blood from both 
auricles, and transmits it partly into the lungs and partly into the aorta, d, d, Arches of 
the aorta, e, Carotid artery-, which distributes the blood to the head. /, Pulmonary vein, 
which conveys the blood from the lungs to the heart, g , Brachial artery, which goes to 
the fore-legs, h , A, Pulmonary artery, in which the blood is submitted to the influence 
of air in the lungs, t, The lungs, j, The stomach, k, Vena portae. I, Intestines, rn. 
Ventral aorta, or that portion of the aorta contained in the abdomen. «, Kidneys, o, 
Liver and vena portae, p, Inferior vena cava, which conveys the blood from all the lower 
part 3 of the body to the heart. < 7 , Superior vena cava, through which the blood of the 
upper parts of the body is sent to the heart. 

Figure G.- Heart of Tortoise. —a , Right auricle. A, Single Ventricle, c, Left auri 

cle. d, d, Pulmonary artery, c, e, Pulmonary vein. Vena cava, g, Right aorta. A, 
Left aorta. __ 






























































PLANTS AND ANIMALS. 


15 


CHAPTER I. 

CHARACTERISTICS OF PLANTS AND ANIMALS. 

16. Plants and animals are distinguished from all unor¬ 
ganized bodies by the process of nutrition and the property 
of reproducing their kind. Plants are nourished by the 
inorganic elements found*in the earth and air around them. 
The materials of their growth are received in the form of 
a liquid or a gas, already prepared for their use. 

17. Animals are nourished by the organic materials of 
vegetables or of other animals. Animals always possess 
a stomach or a digestive cavity, in which their food is 
received, to undergo a process of preparation before it can 
be absorbed into their tissues. 

18. Sensation and voluntary motion are peculiar to 
animals alone, and are therefore called animal functions. 

19. Plants and animals both have a limited period of 
existence, which varies with every species. In some, this 
period is confined to a single day; in many plants, to a 
single summer: while some animals live more than a cen¬ 
tury, and some trees—as the oak and olive—are supposed 
to live a thousand years. 

20. The natural age of man is usually estimated at about 
seventy years, though instances occasionally occur of indi¬ 
viduals who survive an hundred or more years. The 
duration of man’s life is less uniform than that of any 
other class of animals. In some communities, the average 
age at death is only ten or twelve years; in others, it is 
nearly forty. In all cases, individuals and communities 
are long-lived just in proportion as their localities, occu- 

How are plants and animals distinguished from unorganized bodies? How 
are plants nourished ? How are animals nourished ? What do animals always 
possess? What functions are peculiar to animals alone? What is said of the 
period of existence of plants and animals? What is the natural age of man? 
How does it vary in different communities? In proportion to what are com 
uiunities and individuals long-lived? 

2 


16 


CLASS-BOOK OF PHYSIOLOGY. 


pations, and habits of life are favorable to health; foi 
health and life are blessings lent to man only as conditions 
of obedience to the laws of his organization, 


PLATE II. 


GENERAL VIEW OF THE CIRCULATING APPARATUS OF MAN. 

The course and relative positions of the principal arteries and veins of the Systemic 
circulation are shown in this plate. The arteries ccmmence from the great arterial trunk 
called the aorta, and their branches are distributed to all parts of the system. The venous 
branches, which accompany the arteries, unite into two great veins, the superior and infe¬ 
rior vena cava, which convey the blood back to the heart. 

a, The left ventricle of the heart. A, The right auricle, c, The superior vena cava, d, 
The root of the pulmonary artery, e , e, The aorta, which is seen arching backward over 
the heart, and passing downward into the abdomen, where it divides into its two great 
branches, the iliac arteries, through which the blood passes to the lower extremities. /, 
The inferior vena cava, which accompanies the descending aorta and its branches, and 
returns the blood from the lower extremities. The dotted lines represent the outlines of 
the kidneys. 

PRINCIPAL DIVISIONS OF THE AORTA AND VENA CAVA. 

It should be remembered that most of the branches which spring from the great artery 
and vein, are double—that is, each right branch has a corresponding one at the left side 
—:So that there are, for instance, the right and the left carotid arteries, the right and the 
left jugular veins, &c. 

From the arch of the aorta are sent off those arteries which are distributed to the head 
and arms. The principal ones among these are named as follows: 

g. The carotid artery, which ascends in the side of the neck, and divides into the tem- 
noral artery, A, which is distributed in the temple, and the facial artery, i , which supplies 
„ne face; and also sends a branch, called the internal carotid, to the parts within the skull. 

j, The sub-clavian artery, lying beneath the clavicle or collar-bone. That part of the 
continuation of this artery which passes through the axilla or arm-pit, is called the axillary 
artery, k; that which lies in the upper arm, the brachial artery, l; and in the fore-arm, 
it divides into the radial and ulnar arteries, m, n, which are distributed to the hand and 
fingers in the manner indicated in the plate. 

The principal branches of the descending aorta are named as follows. 

The iliac artery, o, which, on passing into the thigh, becomes the femoral artery, p, and 
in the leg divides into the tibial and peroneal arteries, q , r, which form numerous branches 
for the supply of the leg and foot. 

Before dividing into the iliac arteries, the descending aorta gives off several important 
branches; as the cceliac artery, from which the stomach and liver are supplied; the renal 
artery, which goes to the kidneys, and the mesenteric artery, to the intestines; besides 
many other sub-divisious in various parts of its course. 

The branches of the vena cava generally accompany those of the aorta in their distribu¬ 
tion, as shown in the figure, and are often called by the same names. The principal 
divisions of the superior vena cava areThe jugular vein, s, which accompanies the 
carotid artery. The sub-clavian vein, t , which accompanies the artery of the same name, 
and receives the blood from the arm and hand. 

The inferior vena cava, like the aorta, divides into two great branches, the iliac veins, u, 
the sub-divisions of which accompany those of the arteries, and are called by the same 
names. The manner in which the superficial veins ramify and anastomose with each other 
is shown on the upper and lower extremity of the left side. 




Tri¬ 


ll ~ 


HL. 


2.C Kfilloo^ LitT, 


Hartford, Cot 




















































































































OF ANIMAL BODIES. 


19 


CHAPTER II. 

STRUCTURE AND COMPOSITION OF ANIMAL BODIES. 

21. The component substances of animal bodies may be 
divided into fluids and solids: 

22. The fluids are found mostly in the form of chyme, 
chyle, lymph, and blood. About thirty pounds of fluid 
can be drawn directly from a man who weighs one hun¬ 
dred and fifty pounds. By exposure to a process of evap¬ 
oration, the body may then be reduced to twelve or fifteen. 
Perfectly dry mummies are sometimes found to weigh 
only seven or eight. Hence the fluids may be said to 
constitute by far the largest proportion of the body. 

23. The fluids vary exceedingly at different periods of 
life. In youth, they are very abundant, making the form 
plump and round. In old age, they are greatly dimin¬ 
ished, leaving the form shrunken and wrinkled. 

24. The fluids contain in solution the materials for the 
formation of the solid tissues, and are also the medium 
through which all the waste particles are carried out of 
the system. The fluids and solids, being alternately con 
verted into each other, do not differ essentially in their 
chemical elements. 

25. The human body has been found, by chemical 
analysis, to contain the following elementary substances: 
Oxygen, hydrogen, nitrogen, carbon, sulphur, phosphorus, 
silicon, chlorine, fluorine, iron, and sometimes mangane- 
sium, aluminum, and copper. 

26. The first four are most constant and most abundant, 
and are named essential elements. 

27. The solid portions of the body are called tissues. 

IIow are the substances which compose animal bodies divided ? How many 
pounds of fluid may be drawn from the body of a man weighing one hundred 
and fifty pounds? How can the weight of the body be farther reduced? 
When are the fluids most abundant and when least abundant? How many 
elementary substances are there in the human body ? Which are the fout 
essential elements? What are the solid portions of the body called? 


20 


CLASS-BOOK OF PHYSIOLOGY 


28. The tissues, in their primary formations, are made 
up of granules, nuclei, cells, filaments, and fibres. 

29. Granules are particles of various sizes, from immea¬ 
surable minuteness to the ten-thousandth of an inch in 
diameter. Granules are found floating in milk, chyle, and 
other animal fluids, and imbedded in most of the tissues. 

80. Nuclei are the germ and cen¬ 
tre around which cell's are formed. 
{Fig. 1.) 

31. Cells are minute bubbles, vesi¬ 
cles or scales. Their natural shape 
is oval or sphere .’dal. but they often 
become flattened or many-sided by 
pressure, as may be illustrated by 

Fig. i.-parent cells.— filling a vial with a strong solution 
1, b, Secoiidary'ceiis. of soap in water, and then inverting 
c, c, Nuclei. when it will be filled with bubbles, 

each one of which will assume a form in accordance with 
the position it occupies. The cells perform a highly im¬ 
portant process in all animal and vegetable structures. 
The solid portions of plants, and the tissues of animal 
bodies, are formed directly by the deposition of cells, or 
by the indirect elaboration of their fluid contents. They 
are concerned, not only in the functions of nutrition, in 
the development and restoration of parts, but in absorp¬ 
tion and secretion. They are developed into tissues In 
various ways. In some, the cell-membranes become elon¬ 
gated, and are folded and divided into threads or filaments 
of exceeding fineness. 

32. Tubules , or little tubes, are several cells elongated, 
and placed end to end—the partitions being removed. 

33. Filaments, or fibrils, are exceedingly delicate threads, 

composed of minute particles, usually arranged in parallel 
bundles or fasciculi. {Fig. 2.) ^ 

Of what are the tissues made up? What are granules'? Where are gran¬ 
ules found? What are cells? How are cells developed into tissues? What 
are tubules? What are filaments? 



OF -ANIMAL BODIES. 


21 



Fig. 2.—Fasciculi and fibres of cellular tissue. A, White fibrous element, with cell-nuclei visible in it 

B, Yellow fibrous element, showing its branching fibrils. C, Finer fibrils of the yellow element. 

34. Fibres are larger than fibrils, but are similar in othei 
respects. 

35. A tissue is the union or interlacement of one or 
more of these primary structures. 

36. An organ is an instrument composed of tissues, and 
designed for action. Its action is called its function or 
use. Thus, the liver is an organ, and the secretion of bile 
its function. 

37. An apparatus consists of a number of different 
organs, arranged for the performance of some one office. 
The teeth, mouth, stomach, intestines, &c., belong to the 
digestive apparatus. 

38. A system is a connected series of similar parts, such 
as the muscular or the nervous system. 

39. The number of tissues which make up the different 
organs of animals is variously stated, according to the 
minuteness of description which different anatomists adopt. 

Whai abe fibres? What is a tissue?—an organ? What is an apparatus? 
—a system? 

2 * 




22 


CLASS-BOOK OF PHYSIOLOGY. 


40. The cellular or areolar 
tissue (fig. 3) is regarded as 
the primary form of all the 
others. It is formed by the 
crossing or interlacing of mi¬ 
nute fibres, interwoven in eve¬ 
ry direction, so as to form a 
web-like membrane with innu¬ 
merable small spaces, which 
communicate with each other, 
as is shown by filling them 
with air or water. When the 
lung and cellular tissue are 
pierced, as sometimes happens 

Fig. 3.—A magnified representation of a portion ^ fraCtoeS of the ribs, the 

of areoiar tissue. external air passes from the 

lung into this tissue, and continues inflating it till the 
whole body becomes enormously distended with air, caus¬ 
ing suffocation and death. In the progress of disease, the 
watery portions of the blood are sometimes effused into 
this membrane, causing dropsy. When the finger is 
pressed on a dropsical limb, a hollow or depression is pro¬ 
duced by the forcing out of the fluid from this tissue at 
that particular point. 

41. The cellular tissue is found, in every part of the sys¬ 
tem, except in compact portions of bone, teeth, and cartilage. 
Its chief use seems to be to connect together organs and 
parts of organs which require a certain degree of motion 
on each other. It possesses great power of extensibility 
and elasticity. 

42. Various names have been assigned to the cellular 
membrane, corresponding to the different positions in which 
it is found. When inclosing those organs not exposed to 

What tissue is the primary form of all others'? How is the cellular tissue 
formed? How is the cellular tissue sometimes inflated? Where is the cellular 
tissue found? What is its chief use? What different names have been 
given to the cellular tissue ? 



OF ANIMAL BODIES. 


23 


the air, it receives the name of serous membrane, from 
a fluid secreted in it, called serum. In the lining of 
the respiratory passages and of the alimentary canal, it is 
called mucous membrane, from a secretion of mucous 
which is poured out from numerous glands beneath its 
surface. Where it forms a covering for the body, it is 
known as the dermoid membrane, or skin. 


PLATE III 


ORGANS OF CIRCULATION. 


Figure 1.— — Front View of tic Heart. —a, Right auricle, A, Right ventricle, e, Left 
auricle. <r, Left ventricle, e, Aorta. /, Pulmonary artery, g, Superior vena cava. A, k , 
Coronary veins and arteries—the nutrient vessels of the heart. 

Figure 2.- Section of the Heart , showing its Cavities and Partitions or Sq>i d.—a, 

Right auricle, b, Right ventricle, c, Left auricle, d, Left ventricle, e, Aorta. /, Pul¬ 
monary veins, g , Superior vena cava, j, Right pulmonary veins, A, Left pulmonary 
veins. 

Figure 3. - Ideal View of the Circulation. — a, Right auricle, A, The entrance of the 

superior vena cava, c, The inferior vena cava, d, Tricuspid valves, e, Right ventricle. 
/, Pulmonary artery, g, g, Bl anches of pulmonary artery. A, A, Capillary vessels of tho 
lungs, t, Pulmonary veins, j, Left auricle. A, Bicuspid valve. /, Left ventricle, m. 
Arch of the aorta, n, n, Arteries which distribute the blood to the head and upper ex¬ 
tremities. o, Descending aorta, p , p, Capillary vessels of the systemic circulation. 

Figure 4. Capillaries. —This figure represents a highly magnified view of the ar¬ 
rangement of the capillaries, between the branches of the arteiies and veins, as found ic 
on intestinal villus, o, Arteries. A, Veins. 






pl .nr 





7j im 


Hartford. Conn 


w w 

,i/j 

. • 1 Wy 




Pi 

I'M 

i M 








C' w/Jf 







































































THE BLOOD. 


27 


CHAPTER III. 

THE BLOOD. 

43. In all organized beings, tlie process of nutrition is 
carried on by means of a circulati ng fluid. In plants, this 
fluid is called sap; in animals, it is called blood. 

44. The blood of insects is white or colorless. In fishes, 
it is red in the gills, heart, and liver; but nearly colorless 
in the main bulk of the body. In the mammalia, birds, 
and reptiles, it is of a dark purple color when drawn from 
a vein, and of a bright scarlet when it comes from an 
artery. It emits an odor peculiar to the animal from 
which it is taken. 

45. In a few minutes after blood is taken from a living 
animal, it begins to coagulate, and become solid, like a 
soft jelly. If allowed to stand for a few hours, the clot 
will be found diminished in size, but firmer than before, 
and floating in the midst of a yellowish fluid, called serum. 

46. The serum, or liquid, which remains after coagula¬ 
tion, is composed principally of albumen and water. 

47. Albumen forms a very large proportion of the brain, 
the spinal cord, and nerves. It is perfectly colorless when 
pure, and is coagulated or hardened by either heat or acid. 
An example of it may be found in the white of an egg. 

48. The ivater of the blood is always one of its most 
important constituents, and always forms by far the greater 
proportion of its bulk—one thousand parts of the blood 
containing from seven to eight hundred parts of water. 
The amount given off in perspiration, the state of the at¬ 
mosphere, the fluid drank, and many other circumstances, 

How is the process of nutrition carried on in organized beings? What i? 
this fluid called in plants?—in animals? What is the color of the blood in 
insects?—in the mammalia, birds and reptiles? How does the blood coagu¬ 
late? Of what is the serum composed? Of what tissues does albumen form 
a large proportion ? What are some of the characteristics of albumen ? What 
proportion of the blood is water? What circumstances influence the quantity 
of the blood ? 


28 


CLASS-BOOK OF PHYSIOLOGY. 


increase or diminish this portion of the blood, and make 
it subject to frequent variations in quantity. 

49. The clot or crassamentum is composed of fibrin and 
numerous red particles, called blood discs or corpuscles. 

50. Fibrin is white when obtained pure, as it may be 
by repeated washings. Its peculiar property is to coagu¬ 
late spontaneously. It forms the basis of the muscles, and 
is found in lymph and chyle. It is also found in solution 
in the serum, as the blood flows in the vessels of a living 
part, but coagulates soon after the blood is exposed to the 
air, and forms first a jelly-like mass, and then, as the con¬ 
traction progresses, it entangles the coloring matter, and 
presses out the serum—thus forming an imperfect analysis 
of the blood. 

51. The blood discs , which contain the coloring matter, 
have a size and form peculiar to each species of animal in 
which they exist. In man, they are little round cells, flat¬ 
tened like a piece of money, and from T oVoths to ^ gVoths 



Fig 4.— A, Corpuscles of human blood, magnified five hundred diameters, a, Particles collected in a 
columnar form. B, Red particles of the blood of the common fowl, b, A particle seen edgeways. 


of an inch in diameter. (Fig. 4.) In birds, reptiles, and 
fishesf they become necessarily larger, till, in some species 
of fish, they present a surface about six times as large as 
those found in man. The number of the blood discs cor¬ 
respond very much to the temperature of the animal. In 
warm-blooded animals, they form from twelve to fifteen 

Of what is the clot composed ? What is the color of fibrin when pure ? 
What is its peculiar property? In what is it found? How does the coagu¬ 
lation of the blood form an imperfect analysis of the blood? What is the 
color and form of the blood discs? What is the size of the Hood discs in 
different animals? 


THE BLOOD. 


29 


per cent, of the whole mass of the blood; in birds, fifteen 
per cent.; in man, twelve or thirteen per cent. In some 
of the cold-blooded animals—in fishes, for example—they 
form only five or six per cent, of the whole weight of the 
blood. The coloring matter of the blood discs contains 
nearly seven per cent, of iron. In certain diseases, in 
which the proportion of iron is diminished below the natu¬ 
ral standard, the capacity of maintaining animal heat has 
been found correspondingly reduced. In such cases, some 
preparation of iron has been found the best remedy. From 
these facts it is inferred that the blood discs perform an 
important office in maintaining animal heat. 

52. By chemical analysis, the blood is found to have 
nearly the same elements, combined in the same propor¬ 
tions as they exist in the flesh of the animal. It is there¬ 
fore better fitted to renovate the tissues, and to carry nu¬ 
triment to every part of the system—to furnish at one 
point the elements of bone; at another, those of muscle; 
at another, those of brain, and so on. The blood also 
takes up and carries off, through appropriate organs, all 
waste particles; thus maintaining in the body a continuous 
round of organization and decomposition—of growth and 
decay—a perpetual change of particles, new and old. 

CIRCULATION OF THE BLOOD. 

53. The organs by means of which the blood is carried 
from one part of the body to the other, constitute the cir¬ 
culatory apparatus, and the course of the blood through 
the organs is called its circulation. 

54. If we commence with those animals which are low- 

What the number? Under what circumstances is the iron found to be 
diminished ? What is the remedy in such cases ? In what vital process do 
the blood discs perform an important office? What elements is the blood 
found to possess by chemical analysis? What does the blood carry to every 
part of the system? What does the blood take up and carry off? What 
is the circulating apparatus? What the circulation? What is the condition 
of the circu’atory apparatus in different orders of animals? 


30 


CLASS-BOOK OF PHYSIOLOGY. 


est in the scale of organization, we shall find the apparatus 
for circulating the blood exceedingly simple, though it 
becomes more and more complicated as we ascend to 
higher orders. 

55. In insects, the blood is sent to various parts of the 
body by the alternate contractions of different portions of 
a central vessel which runs along: the back, and thus forms 


a rudimentary heart. ( Fig. 



Fig. 5.—Dorsal Vessel of the 
Spider.— a, the abdomen ; b , 
the dorsal vessel or heart; c, a 
trunk passing to the head; d , d, 
vessels communicating with the 
organs of respiration. 


, and fig. 1, Pl. I.). 



Fig. 6.—Circulation in Crustacea. 
—a, heart; gills; c, circulation 
through the body; d, arteries; e, 
veins. 


56. Among the Crustacea—of which the crab, lobster, 
craw-fish, &c., are examples—there is a single sac or ven- ' 
tricle, which receives the blood from the gills, and propels 

it to other parts of the body. (Fig. 6, and Jig. 2, Pl. I.) 

57. In fishes, we have a distinct heart with two cavities 
—an auricle or reservoir, and a ventricle or propelling 
organ. (Fig. 7, and fig. 4, Pl. I.) 

58. Reptiles and the perfect amphibia, such as the frog 


How is the blood sent to the various parts of the body in insects'? How 
in the Crustacea? What is tne circulating apparatus in fishes?—what its 
•’eptiles? 







THE BLOOD. 


31 


and the snake, have two auricles and one ventricle. {Fig. 
8 ? and figs . 5 and 6, Pl. I.) 

<L 



Fig. 7.—Circulation in Fishes.— a, 
heart; b, auricle; c, ventricle; d, circu¬ 
lation through the gills, or lesser circu¬ 
lation ; g, circulation through the body, 
or greater circulation; e, arteries; /, 
veins. 



Fig. 8.—Circulation in Rtr- 
tiles.— a, heart; b. ventri¬ 
cle ; c, c, auricles. 


59. In the mammalia (those animals which nurse their 
young) and in birds, we find parts equivalent to two hearts, 
such as exist in fishes, with a complete double circulation. 
{Fig. 9.) The heart is constructed on the same general 
plan in the entire group of warm-blooded animals, so that 
the heart of an ox, a sheep, or a dog, may be taken to 
illustrate the human heart. 

60. The form of the double heart is somewhat like a 
pear, as represented in fig. 1, Pl. II. and fig. 1, Pl. III. 
In man, it is situated in the front part of the thorax, be¬ 
tween the lungs, with its base or broader part inclining 
obliquely backward and upward towards the right shoulder, 
and its apex pointing forward and to the left side, between 
the fifth and sixth ribs, where its beatings are most dis¬ 
tinctly felt. 

Describe the heart, as found in mammalia and in birds? What is the form 
of the double heart? Where is the heart situated in man? 

3 





32 


CLASS-BOOK OF PHYSIOLOGY. 


61. The heart is protected from friction against other 
organs by a smooth serons membrane, called 'pericardium \ 
by anatomists, and the heart-case by bntchers. The peri* 
cardium is not only spread oyer the external surface of !. 
the heart, but is reflected or doubled on itself in such a 
manner as to form a closed sac or bag, as represented 


in fig. 10. 





fig , 9—Circulation in Man.— a, Fig. 10.— Diagram of tiie Pericardium — 
right auricle; b, right ventricle; a, a, auricles; u, v, ventricles; p,p, pericar- 
c, left auricle; d, left ventricle; dium. 
c, aorta; /, vena cava; g, pulmo¬ 
nary artery; A, pulmonary veins. 

62. The heart itself is divided in the direction of its 
length, into two halves, each representing a single heart. 
The walls of the left half are thicker and stronger than 
those of the right. The reason is obvious: the right 
sends its contents only to the lungs, in its immediate prox¬ 
imity, while the left propels the blood to all parts of the 
system. The walls of the auricles are also much thinner 
than those of the ventricles, which require greater strength 
to act as propelling organs. The office of the auricles is 

How is the heart protected from friction against other organs ? Describe 
the pericardium. How is the heart divided? Which half has the thickest 
and strongest walls? Why are the walls of the left half thicker and stronger 
than the right? How do the walls of the auricle compare with those of the 
ventricle? What is the office of the auricle? 









THE BLOOD. 


33 


only to receive tlie blood as it flows from the veins, and 
their walls are accordingly thin and flabby.* 

63. The anricles and ventricles 
are separated from each other by 
triangular folds of membrane {fig. 

11) on the right side, called tricus¬ 
pid valves (three-pointed), and on 
the left bicuspid (two-pointed) 
valves. These valves are attached 
to the walls of the ventricle by lit¬ 
tle muscular cords, which prevent 
them from being forced up into 
the auricle during the contractions 
of the ventricle. {Figs. 3 and 4, 

Pl. IV.) This simple mechanism ^ 

is so perfect as wholly to prevent ° F the heart- a, right auricle; 

1 J r b, ventricle; c, orifice between the 

the flowing back of the blood into tricuspid valves, d; e, e, ascending 
^ and descending venae cavae;/, pul* 

the auricle. monary artery. 

64. There are also three valves at the entrance of the 
aorta or large artery, and the same number at the orifice 
of the pulmonary artery. These six valves are named 
semi-lunar, from the half-moon shape of the folds of mem- 

How are the auricles and ventricles separated from each other? How 
are the valves attached to the walls of the ventricle? Describe the semi-lunar 
valves. 



* The comparative thickness of the walls of the ventricle, and the 
structure of the valves, may be illustrated most easily by examining the 
heart of some animal. For this purpose, the main vessels should be cut 
off high up, and all the fatty portions carefully removed with a knife. 
The pericardium should be opened one-half the distance round the 
heart, and then turned off to expose the heart, or to be replaced at 
pleasure. The comparative thickness of the walls of the ventricles is 
seen by making a transverse section through the heart, about one-third 
the distance from the apex to the base. By a perpendicular incision 
through each of the external walls to the margin of the auricle, the 
cuspid valves, witji their delicate tendons, are fully exposed. The 
auricles may be cut away at their margins. The semi-lunar valves may 
be exposed, by cutting away successive portions of the aorta and pul¬ 
monary artery. 









34 


CLASS-BOOK OF PHYSIOLOGY. 


brane. They are attached to the walls of the artery at its 
exit from the ventricle, and each fold forms one-third of a ; 
circle. (Figs. 4 and 6, Pl. IV.) 

65. When either set of valves becomes diseased, or fail j 
to perform their office perfectly, the heart becomes irreg- | 
ular and labored in its action, and in some instances snd- j; 
den death ensues. 

66. The arteries, veins, and capillaries are the channels 
of communication between the heart and the various parts ( 
of the body. 

67. The arteries are cylindrical tubes, composed of three ■ 
principal coats—external, middle, and internal. 

68. The external , or resisting coat, forms a strong tough 
investment to the artery, and gives it its power of resist¬ 
ance to the heart’s actions. 

69. The middle, or fibrous coat, is composed of elastic 
tissue, disposed in an oblique direction around the artery, 
and has for its office to equalize the flow of blood through | 
the vessels. If the heart impelled the blood through an 
inelastic tube, at each impulse of the heart a quantity of 
blood would be ejected with a jerk from the other end of 
the tube, and it would cease to flow in the intervals of the 
heart’s contractions. The elasticity of this coat enables | 
the vessel to accommodate itself to the quantity of blood i 
which may be thrown into it, and its alternate distention 
and contraction serves to continue the propulsion of the 
ventricle to the remotest extremities of the arteries with a \ 
constant flow of blood. 

70. The contractile power of the middle coat enables the i 
arteries to close their divided extremities when they have ! 
been cut or torn, so as sometimes to prevent hemorrhage, j 
If the artery be large, a ligature is usually found necessary; ! 

What consequences follow disease of the valves? What vessels are the 
channels of communication between the heart and the various parts of the body ? 
Describe the arteries? What is the use of the external coat of the artery? 

Of what is the middle or fibrous coat composed? What advantages are de¬ 
rived from the elasticity of the middle coat? How is hemorrhage sometimes 
arrested in the smaller arteries , 




THE BLOOD. 


35 


but the smaller branches seldom require it. This con¬ 
traction of the divided end may be increased by the appli¬ 
cation of cold or of stimulating substances, or by simply 
pricking or twisting the cut end of the artery. Fatal 
hemorrhage is thus often prevented by irritating applica¬ 
tions, or by the violence with which the vessels are torn 
asunder. 

71. The internal coat is a thin serous membrane, which 
lines the interior of the artery, and gives it a smooth, pol¬ 
ished surface, along which the blood may flow with the 
least possible amount of resistance from friction. 

72. The arteries gradually diminish in size towards their 
extremities, and finally terminate in minute hair-like ves¬ 
sels, which are too small to be seen with the naked eye. 
As they approach their extremities, the divisions and 
ramifications of the arteries are exceedingly numerous, 
forming frequent communications or anastomoses with each 
other; so that in case of obstructions in one of the main 
trunks, numerous lateral branches keep up a supply of 
arterial blood to parts that would otherwise perish for 
want of it. These anastomoses are very numerous in the 
arteries of the limbs and about the joints. 

73. The veins are composed of three coats, like the arte¬ 
ries, but are much thinner in structure, and do not retain 
a cylindrical form when emptied of their contents, but 
become flattened or collapsed. The veins commence by 
minute vessels in the capillaries, and unite to form larger 
and larger branches, till they terminate in large trunks 
which return the blood to the heart. The velocity of the 
blood in the veins is less than in the arteries, and their 

What is usually necessary to arrest hemorrhage from the large arteries'? 
IIow may the contractions of the divided end of an,artery be increased? 
Describe the internal coat. How do the extremities of the arteries finally ter¬ 
minate? How is the danger of obstruction in the large trunks obviated ? Of 
how many coats are the veins composed? What is their structure? How 
do the veins commence? How does the velocity of the blood in the veins 
compare with that of the arteries'’ 

3* 


3 # 




36 


CLASS-BOOK OF PHYSIOLOGY. 


diameter correspondingly greater. When the veins are 
liable to pressure from the muscles between which they 1 
run, they are abundantly furnished with valves, similar 
in form to the semi-lunar valves of the aorta and pulmo- I 
nary artery. The free margins of the valves are turned f 
towards the heart, so as to prevent any backward movement 
of the blood. By pressing a finger on one of the veins of J 
the back of the hand, near the wrist, and drawing it tow¬ 
ards the knuckle, one or more of these valves can be easily 
found. (Fig. 12.) 



74. The capillaries (hair-like vessels) in man are about 
3 oV oth of an inch in diameter. They are so minutely dis¬ 
tributed to every part of the body, as to render it impossi¬ 
ble to puncture the skin without wounding several of 
these microscopic vessels. In the capillaries, the blood is 
brought in immediate contact with the tissues, and parts 
with its nutritive elements. They are the medium through 
which the functions of nutrition and secretion are per¬ 
formed, and the channels of communication between the 
arteries and veins. Fig. 13 shows a magnified represent¬ 
ation of these vessels in the foot of a frog. Fig. 4, Pl. III., 
displays their arrangement in the human intestine. 

What is said of the valves in the veins? Describe the capillaries? What 
functions are performed through the capillaries? 







































_ 






el » 



































PLATE IV. 


ORGANS OF CIRCULATION.-HEART AND LUNGS. 


Figure 1.- Front View of Heart and Lungs. — Both organs are stripped of their 

envelopes, the pleura and pericardium. The right lung is drawn aside, so as to uncover 
the heart and large vessels. The left lung is deeply dissected, to show the distribution and 
mode of ramification of the air-tubes and blood-vessels. 

a, The larynx. A, The trachea.—The right lung is somewhat shorter than the left, and 
is divided into three lobes, c, rf, e, while the left lung has but two lobes, /, g. The surface 
of the lobes is sub-divided into lobules, by the intersection of great numbers of depressed 
lines, A, Right auricle of the heart, i, Right ventricle, j, Left auricle. A, Left ventricle. 
I , The aorta, m, The pulmonary artery, n , Left pulmonary veins.—These veins are four 
in number, two for each lung; and they return to the heart the blood which has been 
conveyed into the lungs by the pulmonary artery. The division of the pulmonary artery 
into right and left branches, cannot be seen in this figure, being hidden by the aorta, o, 
The superior vena cava, p, Root of the right innominate artery, springing from the arch 
of the aorta, q, Root of the left sub-clavian artery, r, Root of the left carotid artery. 

Figure 2.- Back View of the Heart and Lungs. —a, Larynx, A, Trachea, c, Right 

bronchus, d , Left bronchus, c, Left auricle of the heart. /, Left ventricle, g , Right 
pulmonary veins. A, Left pulmonary veins. Left pulmonary artery, y, Section of the 
aorta. A, Trunks of the brachio-cephalic veins (those which belong to the arms and head). 
/, The opening of the inferior vena cava.—The sub-divisions of the pulmonary arteries and 
veins, and of the air-tubes or bronchi, are seen accompanying each other in the left lung 
in both figures. 

Figure 3.— Bicuspid Valve. —a, Membrane which forms the valve. A, A, Columns ten- 
dins, cords by which the folds are drawn together. 

Figure 4. - A portion of Tricuspid Valve. — a, Membrane of jno of the folds. A, A, 

Columns tendins. c, c, Portions of the walls of the ventricle. 

Figure 5.- Semi-lunar Valves , with Aorta laid open. —a, a, o, Folds of membrane. 

A, A portion of the aorta. 

Figure G.- Semi-lunar Valves. — A , Folds of membrane. B, Valves of aorta. 38 




C.lCelLogQ Lith. 











































THE BLOOD. 


41 


75. The course of the blood in the circulation of man 
may be easily understood, by reference to fig. 3, Pl. III. 
Commencing, we will suppose, with the left ventricle (/}, 
the blood is impelled through the semi-lunar valves into 
the aorta (m), and along its successive branches to the 
microscopic net-work of the capillaries (p p), which ramify 
through all the tissues of the body. In the capillaries, the 
blood parts with its nutritive elements, becomes venous, 
and is collected into the small veins, and flows through 
their converging branches into the main trunks, the venae 
cavae (6 and c), and finally into the right auricle (a). From 
the right auricle it is emptied through the tricuspid valves 
( d ) into the right ventricle (e). This completes the great 
or systemic circulation. 

76. From the right ventricle the blood is impelled 
through the semi-lunar valves into the pulmonary artery, 
and along its branches (g g) to the capillaries of the lungs, 
to be exposed to the action of the air. From the pulmo¬ 
nary capillaries the blood enters in converging streams the 
pulmonary veins (i i), which carry it to the left auricle (/), 
and this completes the lesser or pulmonary circulation. 
It is then emptied through the bicuspid valves (Jc) into the 
left ventricle, where it started on its course. 

77. At each contraction, the heart of a man in middle 
age, whose blood averages about twenty-eight pounds, 
empties itself of two ounces of blood, with a propelling 
force of about four and one-quarter pounds. The heart 
of such a person contracts about seventy-five times in each 
minute; so that, in every three minutes, twenty-eight 
pounds and two ounces pass through the heart, or a quan¬ 
tity equal to the weight of the entire blood in the body. 

Describe the course of the blood in the circulation of man. What changes 
take place in the capillaries'? What is the course of the blood from the right 
ventricle ? Of how much blood does the heart of a man in middle age empty 
itself at each contraction ? What is the amount of the propelling force of thf 
heart 1 ? How many times does the heart contract in a minute? How long a 
time will twenty-eight pounds of blood require to pass through the heart ac¬ 
cording to this estimate'? 





42 


CLASS-BOOK OF PHYSIOLOGY. 


78. By the rapidity with, which poisons are transmitted 
from one part of the system to another, it is* estimated that 
in man the blood completes its entire circuit of the arte¬ 
ries, capillaries, and veins of the greater or systemic cir¬ 
culation, and then of the pulmonary circulation, to its 
original starting point, (the left ventricle,) in less than one 
minute. 

79. The frequency of the heart’s action varies at differ¬ 
ent periods of life, being most frequent in infancy, and 
diminishing to old age. During the first year, the average 
number of pulsations in a minute is from one hundred and 
thirty to one hundred and fifty. At the seventh year, the. 
number is from ninety to eighty-five; in middle life, it is 
about seventy-five; in old age, it is as low as sixty, or 
even fifty. In the female, the heart beats more frequently 
than in the male. The action of the heart is also accele¬ 
rated or retarded by various circumstances affecting the 
nervous system. It is quicker after th^n before eating, 
and slower during sleep than when awake; in the evening, 
than in the morning; and in the sitting, than in the stand¬ 
ing position. Fear, anger, and the stronger passions, move 
the heart to violent action. Melancholy or sorrow retard 
it, both in force and in frequency. Hence a temper of 
uniform good-nature is always conducive to long life, 
while frequent indulgence in fits of passion induce prema¬ 
ture disease, and sometimes sudden death. 


How long a time will be necessary, if we form our opinion from the rapidity 
with which poisons are transmitted ? What is the frequency of the heart’s 
contractions during the first year?—the seventh?—in middle life?—in old 
age ? What other circumstances affect the frequency of the heart’s action ? 
What temper of inind is conducive to long life ? 









t 









ORGANS OF RESPIRATION 




Figure 1.- Front View of the Cavity of the Thorax. —a, A, c, Lobes of the right lung. 

d , c, Lobes of the left lung. /, /, The diaphragm, clothed with the pleurae, g, g, Section 
of the ribs. A, Appendage to the breast-bone, called the ensiform cartilage. *, The heart 
covered by the pericardium, the left lung being drawn aside to display it. A, k , Internal 
jugular veins. I, Z, Carotid arteries, m, Larynx. 

Figure 2.- Posterior View of the Cavity of the Thorax.-^a, The larynx. A, The tra¬ 

chea. c, c, The right and left bronchi, d, aorta, e, The heart. /,/, The diaphragm. 

Figure 3.- Lungs of a Frog.—a, Hyoidean apparatus, b, Cartilaginous veins at the 

root of the lungs, c, c, Pulmonary sacs. 

Figure 4.- Section of the Lung of the Turtle, 








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INSPIRATION. 


47 


CHAPTER IV. 

RESPIRATION. 

80. Kespiration is that process by which a mutual' 
interchange of elements is effected in every living being 
between its circulating fluid and the air. Plants cannot 
be perfected unless the ascending sap is exposed to its 
chemical action, and animals cannot maintain life without 
a perpetual renovation of the blood by its purifying influ¬ 
ence. There is in every class some provision for exposing 
the nutritive fluids to the action of this essential element 
of vitality. 

81. In plants, the process of respiration takes place in 
the leaves. Carbonic acid (which is composed of carbon 
and oxygen) is absorbed from the air, and decomposed:— 
the oxygen is set free or escapes from the leaves, and the 
carbon is absorbed by the sap, and transformed into the 
various tissues of the plant. 

82. In animals, the process is reversed. Oxygen is ab¬ 
sorbed, and carbonic acid, which is pernicious to animal 
life, is given off. Thus the two great kingdoms of nature 
mutually furnish those elements which are essential to the 
life of each other. Plants purify the air for the use of an¬ 
imals, and maintain in it a supply of that element, without 
which animals cannot exist. Animals, in turn, furnish the 
essential element for the growth of all vegetable struct¬ 
ures, by parting with that which is useless and even 
poisonous to themselves. 

83. In animals, the necessary condition for the function 
of respiration is a membrane supplied with the circulating 

What is respiration ? What is said of the necessity of respiration in plants 
and in animals'? How does the process of respiration take place in plants'? 
Of what is carbonic acid composed ? How do plants dispose of the oxygen ? 
—how the carbonic acid ? How do animals dispose of the oxygen ?—how the 
carbon? How do plants affect the air? What is the necessary condition 
for the function of respiration in animals ? 

4 




48 CLASS-BOOK OF PHYSIOLOGY. - 

fluid on. one side, and tlie air on the other. But the same 
principle is so modified in the different groups of animals 
as to adapt it to their various modes of life. In some, this 
is the only condition; in others, there is a complication of 
organs, all tending to make this condition more perfect. 

84. Thus, in the lowest groups, ot 
which the hydra is an example {fig. 14), 
the respiration takes place through the 
whole surface of the animal, and is 
called cutaneous respiration. This kind 
of respiration is found to some extent 
in all the higher orders of animated 
beings, and is of no inconsiderable 
importance even to man. In many 
of the cold-blooded animals it is 
equally important with that performed 
by the special organs of respiration. 
The frog, for example, will live longer 
Fi g . i 4 .—The Hydra, or with his mouth and nostrils com- 
Fresh-water Polype. pi^ly closed, than when his skin is 

coated with a substance through which the air cannot 
oenetrate, 

85. All the animals which possess a special organ oi 
respiration may be divided in two large groups, viz: 
water-breathing and air-breathing animals. Each of these 
groups also presents two distinctive modifications of the 
respiratory organs, quite unlike each other. 

86. In the lowest group of water-breathing animals, the 
respiratory organs consist of prolongations of the cutane¬ 
ous covering into fringes, such as are represented in the 

How is this principle modified in different groups of animals'? How does 
respiration take place in the hydra ? What is this kind of respiration called ? 
[n what other orders of animals is this kind of respiration found ? What is 
said of its importance in cold-blooded animals ?—in the frog ? In how many 
large groups may all the animals which possess a special organ of respiration 
be divided? What modification in each of these? Describe the respiratory 
organs in the lowest group of water-breathing animals. 







RESPIRATION. 


serpula. {Fig. 15.) In different orders of this group of 
animals, the fringes are found in very different forms. In 
some, they are attached to the head, and in others, to the 
side, and serve the double purpose of 
respiratory and locomotive organs. 

87. In fishes, which belong to the 
highest group of water-breathing ani¬ 
mals, the respiratory organs consist of a 
series of arches attached to the head, 
each of which is supplied with a vast 
number of thin elongated plates, collect¬ 
ively forming gills. 

88. The gills of fishes are made up 
of numerous little fibres, set close to 
each other, like the barbs of a feather. 

Each fibre contains a slender plate of 
cartilage, which gives it mechanical sup- F & is .—'the serpula. 
port, and enables it to preserve its shape while moved by 
the streams of water which are perpetually rushing through 
the gills. On the surface of the fibres are distributed myr¬ 
iads of blood-vessels, spread over every part like a delicate 
net-work. The whole extent of this surface, exposed to 
the action of air absorbed from the water, is exceedingly 
great. In the skate it is at least equal to the whole sur¬ 
face of the human body. The water itself does not act 
on the respiratory membrane, but is merely the vehicle by 
which the air is brought in contact with it. It is well 
known that fishes cannot live any length of time in a 
limited quantity of water which has no access to fresh air. 
When they are removed from the water, the filaments of 
the gills almost instantly flap together, and adhere in such 

What is said of the form and attachment of the fringes ? Describe the respi¬ 
ratory organs of fishes. The gills of fishes are made up of what ? How do the 
fibres preserve their shape ? What are distributed on the surface of the fibres ? 
What is said of the extent of this surface exposed to the action of the air 
absorbed from the water? How great is it in the skate? Does the water 
itself act on the membrane ? What does ? How are fi>hes effected by being 
kept in water which has no access to fresh air? 





50 


CLASS-BOOK OF PHYSIOLOGY. 


a manner as prevents the exposure of a great portion of 
their surface to the air; but the portion which is exposed 
shortly becomes so dry, that the action of the air on the 
blood is soon suspended, and death ensues from imperfect 
oxygenation. 

89. In insects, which 
form the lowest group 
of air-breathing animals, j 
there is a special provi¬ 
sion for conveying air 
to the circulating fluids 1 
through tubes of thin | 
delicate membrane. (Fig. j 
16.) The abdomen of an i 
insect is made up of a 
series of joints, each of 
which is composed of two 
plates, one on the uppet t 
and one on the lower 
side. At the edges of 
each joint, where the two 
plates meet, there is an 
opening, called the stig¬ 
ma, through which the 
air passes into the tubes. 
These tubes extend to 
every part of the insect, 
and convey air to all the 
tissues, forming a very re¬ 
markable substitute for 
a circulation of the blood 
through a special organ of respiration. 

90. The highest group of air-breathing animals possesses 
a distinct lung, which is found greatly modified in the 

What takes place when they are removed from the water to the air ? What 
is the cause of death ? How is air conveyed to the circulating fluids of insects ? 
Describe the air-tubes of insects. What do the highest group of air-breathing 
animals possess ? 












RESPIRATION. 


51 


different classes of animals that belong to this group. The 
lung is seen in its sim¬ 
plest condition in the 
snail, {fig. 17,) where 
it consists of a respira¬ 
tory sac with a blood¬ 
vessel distributed on its d 
surface. 

91. In frogs, the lungs 
consist of two bags, on 
the walls of which are 

,. , Fig. 17.—Interior of a Snail. — a y the heart; 6, 
cells 01 DUt Very slight large blood-vessels branching over the sac, c; d, 
i 4 . 1 , xL j? artery which conveys the blood to the general sys- 

depth J the process 01 tem; e, part of the stomach; /, the liver. 

respiration is carried on through the membrane that forms 
the cells, {Fig. 8, Pl. Y.) 

92. In turtles, the interior of the lungs is divided into 
several cavities which communicate with each other. 
{Fig. 4, Pl. V.)* 

In what animal is the lung seen in its simplest condition 1 Describe the 
respiratory organs of a frog—a turtle. 

* A very beautiful preparation, to show the distribution of the blood¬ 
vessels over the membrane of the lung 1 , together with the membrane 
itself, may be prepared from the lungs of a turtle. Procure a turtle at 
least six or eight inches in length, cut off the head, and immediately 
saw the lower shell from the upper at the sides, and then with a knife 
dissect off the muscles from the shell. When the shell is removed, 
almost the first object that arrests the attention is the heart, still per¬ 
forming its functions with as much apparent regularity as if nothing 
had happened, which it will continue to do for several hours, though its 
action grows more and more feeble. On either side of the heart, and 
partly under the scapulae, the lung may be seen in a collapsed state. A 
quill should be inserted into the trachea, and the lungs inflated, for the 
purpose of rendering their position more apparent, when they can be 
easily removed with the scissors, though it must be remarked that the 
slightest scratch spoils the preparation. As soon as the lungs are 
removed, they should be inflated to their utmost capacity, a ligature 
applied to the trachea, and then hung in the air to dry. In half an hour 
you have an exceedingly handsome and useful preparation, which may 
be preserved for anv length of time. 

4* 








52 


CLASS-BOOK OF PHYSIOLOGY. 




93. In birds, the respiratory 
apparatus consists of two lungs, 
which are made up of numer¬ 
ous cells. The air also passes 
through the lungs into large 
sacs along the abdomen, and 
even into the bones. {Fig. 18.) 
Respiration in birds is more 
frequent than in any other class, 
and their movements are cor¬ 
respondingly more active. The 
large amount of air contained 
in the sacs and bones of birds 
rnnst also serve to give them 
more lightness and buoyancy 
for their aerial flights. 

F 94. The capacity of the 
lungs, as a respiratory organ, 
depends in each group of animals on the extent of the 
respiratory membrane, which is invariably increased in 
proportion as the cells become more numerous in a given 
space. Thus, in the entire group of warm-blooded ani¬ 
mals, where the function of respiration is at its highest 
perfection, we find an almost infinite number of cells. 

95. In the human lungs it is estimated 
that there are at least six hundred millions 
of air cells, collectively presenting a surface 
equal in extent to about thirty times the 
whole surface of the body. Each cell, as is 

ng. i 9 ._air-cell, represented in fig. 19, is constructed on the 

branching < overTt. s san? e P^ ai1 as single air-sac of the snail, 
and consists of a thin delicate membrane, with an artery 


Fig. 18.— Lungs of the Ostrich. — a, 
the heart; b, the stomach; c, c, the 
intestines; d , the trachea or windpipe; 
e, e, the lungs; /, /, /, air-cells, in 
which are also seen the orifices of the 
tubes through which these air-cells 
communicate with the lungs. 


Describe the respiratory organs of a bird. How do birds compare with 
other animals in the frequency of their respirations? What special benefit 
do birds derive from the large amount of air contained in their sacs and bones? 
Upon what does the capacity of the lung depend ? In what group of animals 
are the air cells most numerous? How many air cells are there in the 
>»uman lungs? How is each air cell constructed ? 



RESPIRATION. 


55 


distributed on its surface in minute capillary vessels, which 
terminate in veins that carry the blood back to the heart. * 

96. The whole substance of the lungs is thus made up 
of these minute cells, with their air and blood vessels. 

97. The lungs are supplied 
with air through the larynx and 
trachea. {Fig. 20.) 

98. The larynx is an irregular 
cartilaginous tube, forming the 
upper extremity of the windpipe , 
as the whole tube is comnlonly 
called. The larynx is situated 
immediately below the root of 
the tongue, and forms the pro¬ 
tuberance in the front part of the 
neck, called u Adam's Apple." 

The larynx gives passage to the 
air which, is inhaled into the 
lungs or exhaled from them, and 
contributes essentially to thopro- Fig. 20.— a, the larynx ; b, the trachea ; 

t , • r. -i c, bronchial tubes; d. the left lung. 

auction 01 vocal sounds. 

99. The trachea is composed of about eighteen cartila¬ 
ginous rings, connected together so as to form a tube, 
which is capable of maintaining a uniform, size. 

100. On entering the chest, the trachea divides into two 
trunks, called bronchi, one of which goes to the right and 
the other to the left lung. As soon as the bronchi enter 
the lungs, they branch off into numerous divisions and 
sub-divisions, their ultimate extremities terminating in 
air cells. {Fig. 1, Pl. YI.) 

101. The human lungs occupy the greater part of the 



Of what is the whole substance of the lungs mainly made up? How are 
the lungs supplied with air? Describe the larynx. How is the larynx situ¬ 
ated, and what is it sometimes called ? What other use has the larynx besides 
to give passage to the air? How is the trachea formed ? How does the tra¬ 
chea divide on entering the chest ? How do the bronchi divide ? Where 
are the lungs placed in man ? 





54 


CLASS-BOOK OF PHYSIOLOGY. 


chest, the heart being the only organ of much volume 
which is included in it. The size of the lungs in different 
individuals corresponds very nearly to the capacity of this 
cavity. Hence, persons with full broad chests rarely suf¬ 
fer from weak or consumptive lungs, while those who have 
narrow and contracted chests are as seldom exempt from 
these evils. 

102. The chest, or thorax , is a cavity closed on all sides 
from the entrance of air, and its bony walls afford an ad¬ 
mirable protection to the delicate organs included within it. | 

103. The walls of the tho¬ 
rax {fig. 21) are formed by 
the breast-bone in front, by the 
ribs and spine on the sides and 
back, and by the diaphragm 
below. 

104. The ribs, to the num- j 
ber of twelve on each side, are 
attached to the bones of the 
spine by slightly movable 
joints, and to the breast-bone 
by flexible cartilages. The ribs 
are also connected to each oth¬ 
er by the intercostal muscles. 

105. The diaphragm {fig. 5, 
Pl. YI.) is a large muscular 
partition, which separates the 
chest from the abdomen. 

106. The internal surface of the chest is lined through¬ 
out with a serous membrane, called the pleura , which is 
reflected over the external surface of the lungs. A serous 
fluid is constantly exhaled from this membrane, causing 
the parts to glide on each other free from friction. * 

How may we judge of the size of the lungs in different individuals 1 De¬ 
scribe the chest. How are the walls of the thorax formed ? Describe the 
ribs—the diaphragm. How is the internal surface of the chest lined ?— and 
how is it kept moist 1 




































» 











































PLATE VI. 


ORGANS OF RESPIRATION. 

Figure 1.- The Larynx , Trachea , and Bronchi. — a , The larynx, b , The trachea. 

c, c, Bronchi, d, d, d, e, c, e, Outlines of the lungs. /, /, /, &c., Bronchial tubes.—These 
tubes continue to ramify, decreasing in size, until they can only be distinguished by the 
microscope, g, g, g , Lymphatic vessels and ganglia. 

Figure 2.- A Portion of the Tissue of the Lungs , Showing the blood-vessels, capil¬ 

laries, and air-tubes, magnified fifty diameters.—A vein, a, is represented ramifying with 
an artery, b , around the intricate air-cells, c, c. 

Figure 3. - The Plural Surface of a Portion of Lung , magnified three diameters, 

showing the form and great abundance of the air-cells. 

Fioure 4.- Plural Surface enlarged 

Figure 5. - The Diaphragm , separated from the Body. — a , The right vault of the 

diaphragm, which is higher than the left. i>, b , The right and left crura or pillars of tbo 
diaphragm, by which it is attached to the spinal column. 

Figure G.- Lateral Vieio of the Outlines of the Thorax and Abdomen. —This figure 

is intended to show the respective positions of the diaphragm and the walls of the chest 
and abdomen, in inspiration. The dotted lines, a, a indicate the contour of the front of 
the chest and abdomen, when the chest is filled with air after inspiration, b , b , The line 
of the diaphragm, when it is contracted and flattened in inspiration, pressing down the 
abdominal contents, and causing the abdomen to project, c, c, The line of the chest and 
abdomen, after the air is expired, d, <Z, The arch of the diaphragm, when relaxed in 
expiration, rising into the interior of the thorax, and drawing inward and downward 
its point of attachment to the front of the body, c. 












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KESPIKATION. 


59 


107. In the process of respiration, the cavity of the 
chest is constantly increased and diminished in size by the 
alternate elevation and depression of the ribs and dia¬ 
phragm, as explained by fig. 6, Pl. YI. 

108. When the lungs are empty, and the respiratory 
organs at rest, the ribs hang downward and inward, and 
the diaphragm extends upward into the cavity, reducing 
it to its smallest capacity. In the act of respiration, which 
inflates the lungs, the ribs are elevated, increasing the 
diameter of the cavity, and the diaphragm is at the same 
time depressed, increasing its length; thus making the 
capacity of the chest greater in all directions. 

109. As the cavity of the chest is enlarged, air rushes 
into the lungs, and inflates them, to fill it just as perfectly 
as when at rest. The lungs are thus comparatively pas¬ 
sive in the respiratory movements, always accommodating 
themselves to the size of the cavity in which they are con¬ 
tained. The active process of respiration is performed by 
the respiratory muscles (d, e, i , fig. 21,) attached to the ribs 
and by the diaphragm. 

110. When the ribs are confined by a tight dress or 
otherwise, respiration is carried on mainly by the dia¬ 
phragm. When the abdomen is so closely confined or so 
distended as to prevent the descent of the diaphragm, res¬ 
piration is performed by the respiratory muscles attached 
to the ribs. 

111. It is therefore a law of our organization that, all 
parts of our dress should be loose about the chest and ab¬ 
domen. When the fullest action of the respiratory organs 
is in any way restrained, respiration becomes correspond- 

How is the cavity of the chest increased and diminished in size? What is 
the position of the ribs and diaphragm when the respiratory organs are at 
rest 1 What change takes place in the act of respiration ? How is the chest 
filled when it is enlarged 1 By what organs is the active process of respira¬ 
tion performed ? How is respiration carried on when the ribs are confined 1 
How when the diaphragm 1 What law of our organization do these parts 
teach us ? 



60 


CLASS-BOOK OF PHYSIOLOGY. 


ingly more frequent and more laborious. For this reason, 
all persons who diminish to any extent the capacity of the * 
chest or of the abdomen, breathe oftener than is natural, 
and with slight exertions pant for breath, like one who has 
been taking most violent exercise. 

112. Under ordinary circumstances, the number of inspi¬ 
rations of an adult are from fourteen to eighteen in each 
minute. In mental excitement or active exercise, they 
become more frequent. Infants and young persons breathe : 
more rapidly than adults. 

113. The average quantity of air taken into the lungs 
at each inspiration is about twenty cubic inches; at six¬ 
teen inspirations in each minute, twenty thousand cubic 
inches of air pass through the lungs in an hour—making I 
two hundred and sixty and one-third cubic feet in a day. 

114. As the air passes through the lungs, it parts with 
about one-fourth of its oxygen, and receives nearly an 
equal amount of carbonic acid. It is also saturated with 
watery vapor, and warmed to nearly the same temperature 
as the blood. 

115. In this process, the venous blood is purified of the 
waste and worn-out particles, which are taken up from the 
capillary circulation in the tissues, and converted into 
arterial blood. 

116. It is estimated that in every minute a quantity of 
blood equal to the whole amount in the body is subjected I 
to this renovating process in the lungs, and in every 
twenty-four hours about twenty ounces of watery vapor 
and six ounces of carbon are exhaled from the lungs. 


When the aetion of the respiratory organs is in any way restrained, what is the 
effect on respiration ? What is the number of respirations in adults ? How is it 
affected by exercise or by excitement ? How much air is taken into the lungs 
at each respiration ? How much air will pass through the lungs in an hour? 
—in a day ? How is the air changed in passing through the lungs ? What 
change takes place in the blood during this process? How much blood 
is subjected to this renovating process every minute? What is exhaled 
from the blood ? 




RESPIRATION. 


61 


117. If the lungs become diseased, so that their func¬ 
tion is imperfectly performed, or if the air we breathe is 
already charged with impurities, which have escaped from 
the lungs, or if there be an insufficient supply of air, the 
whole system suffers. The blood is burdened with an ac¬ 
cumulation of impurities, and the nervous system becomes 
depressed and inactive for the want of pure arterial blood, 
its natural stimulus.* 

118. For this reason, persons who sleep in small imper¬ 
fectly-ventilated rooms, feel languid and oppressed in the 
morning, instead of being refreshed and invigorated. 

119. In churches and public assemblies, when there is 
an insufficient supply of pure air, a feeling of fatigue, lan¬ 
guor, and head-ache is very soon experienced. 

120. A due supply of pure air may be regarded as one 
of the most essential conditions of healthy respiration. 
Life cannot be sustained for any considerable time with¬ 
out air, nor can it be continued in carbonic acid gas. 
Therefore, every apartment we occupy, whether public or 
private, should be provided with reliable means for con¬ 
veying off the poisonous gas and supplying the pure air. 

121. When we consider the delicate structure of the 
lungs, and the absolute necessity of efficient ventilation 
we are not surprised that one-fourth to one-third of our 
race are scourged with lung diseases; since little or no 
care has been taken to obey this imperious law of animal 
existence. 

122. Every room not provided with that noble ventila¬ 
tor, a fire-place , should have an aperture for the entrance 
of pure air, and another for the exit of the gases thrown 

If the lungs be diseased or the air be impure, whatris the effect ? What is 
the effect of sleeping in poorly-ventilated apartments? How are public assem¬ 
blies affected by impure air? What is said of the importance of a due 
supply of pure air ? With what should every apartment we occupy be pro¬ 
vided ? What proportion of our race are scourged with lung diseases ? How 
should every room be ventilated ? 

5 





02 


CLASS-BOOK OF PHYSIOLOGY. 


off by respiration; and no family which neglects these 
conditions of health, can expect exemption from disease.* 

* A very interesting experiment, to illustrate the importance of ven- I: 
tilation, may be made by lowering a lighted taper or candle attached to ; 
a flexible wire into an open-mouthed glass jar, holding one or more 
pints. In a very few minutes carbonic acid will be found sufficient to 
extinguish the taper. That it is carbonic acid may be ascertained by ; 
pouring into the jar lime-water, which immediately becomes turhid from 
the formation of carbonate of lime. That carbonic acid is also pro¬ 
duced by respiration may be made to i ppear by filling and inverting the 
jar in water; then pass the end of a tube (or, if nothing better be at \ 
hand, an open straw,) under the jar, and breathe through the tube into 
the jar till the water is entirely displaced. The hand, or a piece of 
glass or of brown paper, must now be put snugly on the mouth of the ; 
jar, which is to be inverted and placed on the table. On removing the ; 
hand, plunge the taper into the respired air, and it will be instantly 
extinguished. The necessity for a supply of oxygen may be shown 
by inverting the jaV, and passing up the lighted taper. As fast as the 
oxygen is consumed, the nitrogen, which is lighter than atmospheric 
air, occupies the upper portion of the jar, causing the taper to grow 
dim or be extinguished, according to the position in which it is held. 







ANIMAL HEAT. 


63 


CHAPTER V. 

ANIMAL HEAT. 

123. The power of maintaining animal heat is closely 
allied with the process of respiration. In those animals 
which possess the most perfect development of the respira¬ 
tory organs, the animal heat is maintained at a uniform 
temperature, whatever may be the variations of tempera¬ 
ture in the surrounding medium. 

124. In birds, respiration is more active than in any 
other class of animals, and their temperature is uniformly 
higher than any other, ranging from 106° to 112° Fahren¬ 
heit. In the mammalia, it is from 95° to 105°. In man, 
at adult age, it varies, in different individuals, from 98° 
to 100°. In fevers, it is several degrees higher: in scarlet 
and typhus fevers, as high as 106° or 107°. In health, it 
is about one degree and a half lower during sleep than 
when awake. Hence we always require additional cloth¬ 
ing during sleep. 

125. In the young of all animals, the temperature is a 
few degrees higher than in the adult, and respiration is 
correspondingly more frequent; but the sensibility to cold 
is much greater, and consequently the power of resisting 
it much less. For this reason, when young animals are 
exposed to a low temperature, without protection, the ani¬ 
mal heat rapidly diminishes, and, if artificial heat be not 
afforded, death ensues. 

126. Those animals which possess the power of main¬ 
taining a uniform standard of temperature, are called warm - 

What relation has the power of maintaining animal heat to the process of 
respiration. How does the respiration and temperature of birds compare with 
other animals ? What is the temperature in the mammalia ?—in man ? What 
is it in fevers? What during sleep ? What is the temperature and respira¬ 
tion of young animals ? How do they bear exposure to cold ? What are those 
animals called which possess the power of maintaining a uniform temperature? 




64 


CLASS-BOOK OF PHYSIOLOGY. 


blooded animals. Eeptiles, fishes, and all the lower order 
of animals, are cold-blooded. 

127. In the snail, whose respiratory apparatus we have 
seen is exceedingly simple, the temperature is very little 
above that of the surrounding air. The temperature of 
fishes is always nearly the same as that of the wateb, 
rising or falling with the warmth or cold of the sea, river, 
or lake which they inhabit. In reptiles, which come near¬ 
est to warm-blooded animals in the development of the 
respiratory organs, there is the power to maintain the 
temperature of the body a few degrees higher than the 
surrounding medium, though this cannot endure a very 
low temperature without becoming torpid. 

128. In some cold-blooded animals, a most remarkable 
provision exists for preserving life when the temperature 
of the body is reduced below the freezing point. As the 
cold increases, the organs become more and more inactive, 
until at length all the animal functions cease, and torpidity 
ensues. Some species of insects and fishes may be frozen 
solid like ice, and yet retain life, and again become active 
when exposed to a proper degree of warmth. The feez¬ 
ing appears to produce no chemical change, either in the 
tissues or the fluids; it merely suspends the operation of 
their affinities until, by a return of warmth, they are ex¬ 
cited to action.* 

What are those called which do not possess this power 1 What order of ani¬ 
mals are cold-blooded 1 What is the temperature of the snail ? What of 
fishes'? What is the temperature of reptiles'? What remarkable provision 
exists in some cold-blooded animals for preserving life at a low temperature 1 
What examples are given ? How is this fact explained ? 


* Some very interesting phenomena have been observed in certain 
warm-blooded animals, which hybernate or spend the winter in a semi- 
torpid state. One of these hybernating animals, common in New Encr. 
land, is a species of marmot, usually called woodchuck. This animal 
enters his den or burrow about the first of October, closing the entrance 
after him with hard-packed earth. There he remains until about 
the first of April, most of the time enjoying a very profound sleep 








ANIMAL HEAT. 


65 


129. A comparative view of the process of respiration, 
in connection with the development of animal heat, very 
clearly shows that the lungs, under the influence of the 
nervous system, are the organs which maintain the tem¬ 
perature of the body. The various tissues, together with 
the food, supply the blood with carbon, which combines 
with the oxygen of the respired air to form carbonic acid, 
and produce one hundred and thirty-five degrees of heat 
for every ounce of carbon. The chemical combination in 
this process is essentially the same as that of combustion. 

130. The lungs, however, must not be regarded as the 
only source of animal heat. For it is probable that cer- 

What does a comparative view of the process of respiration, in connection 
with the development of animal heat show 1 With what does the carbon of 
the blood combine ? What is formed by this process ? How does it compare 
with combustion ? Are the lungs the only source of animal heat 1 

and breathing just often enough to keep himself comfortably warm. 
During the five months which he remains in this condition, his whole 
number of respirations does not exceed those of eight or ten days of 
activity in the summer months. All hybernating animals become enor¬ 
mously fat in the autumn before they begin their “ winter’s-nap.” This 
fat, which contains a very large proportion of carbon, is gradually ab¬ 
sorbed, and combined with the oxygen of the lungs, in order to main¬ 
tain the necessary temperature; and the animal comes forth from his 
hiding-place in the spring greatly emaciated, and with a most excellent 
appetite. During the long period of his sleep, digestion and the other 
animal functions not necessary to respiration have been entirely suspend¬ 
ed, and the small supply of oxygen indispensable to his diminished 
respiration has been obtained from the air which penetrates through the 
earth to his burrow. These animals possess no peculiarity of structure 
by which they are particularly suited to this mode of life. They seem 
rather to have an instinctive impulse to adopt this economical method 
of passing the winter, because, during that season, their usual supply 
of food can no longer be obtained. Indeed, some other animals, whose 
habits do not commonly lead them to hybemate, have the power of pro¬ 
longing life in a similar manner; and the same species which hybernate 
in a cold climate will not do so in a warmer one. This habit of sleep¬ 
ing through the winter seems, therefore, by a wise provision of the 
Creator, to be given to certain animals, in order to supply the failure of 
all other means of maintaining life. 





66 


CLASS-BOOK OF PHYSIOLOGY. 


tain chemical changes, resembling those in the lungs, are 
constantly taking place throughout the tissues of the body, 
whereby a small amount of heat may be evolved. 

131. The variations of atmospheric temperature have 
long since been observed to exert an important influence 
over the health of the lungs. The diseases of the lungs 
prevail most during those months and *n those localities 
where the weather is the most variable, and diminish most 
in proportion as the weather becomes more uniform. 

132. To guard against lung diseases, constant care and 
vigilance must be exercised to preserve the warmth of the 
body as uniform as possible by artificial means. The 
clothing during winter should be sufficient uniformly to 
protect the body against sudden changes, and it should not 
be changed too suddenly or at too early a season for the 
thinner habiliments of hot weather: for it is much better 
to suffer a little inconvenience from the heat of flannels, 
in the spring, than to risk injury to the lungs by taking 
them off, as is too often done on the first warm day. 


What other source is there 1 What causes affect the health of the lungs 1 
When and where do diseases of the lungs prevail most 1 What is necessary 
to guard against lung diseases'? What care should be exercised in regard to 
clothing? 











DIGESTION. 


67 


CHAPTER VI. 

DIGESTION. 

133. Digestion is that process in animals by which the 
food is prepared for the nutrition and growth of the body. 

134. The food of plants is derived from the earth and 
air aronnd them, in a liquid or gaseous state, and is already 
adapted to their use. But the materials from which animals 
derive their nourishment require a certain degree of pre¬ 
paration before they can be taken up by the nutritive fluid. 

135. All animals are therefore provided with organs by 
which their food is acted upon, so as to fit it to be con¬ 
veyed into their systems; and in no organs of the body is 
the wisdom and skill of the Creator more manifest than in 
the means with which every animal is provided for secur¬ 
ing a subsistence. 

136. In those animals which live on food that requires 
but little preparation, the organs of digestion are very 
simple. In the class of polypes , for instance, a single sac 
or cavity, in which the food is dissolved, is all that is 
required. 

137. In the higher orders, there is an apparatus for 
masticating or grinding the food; and instead of the sin¬ 
gle digestive sac of the polype, there are three distinct 
cavities: in the first, the food is mechanically divided; in 
the second, it is reduced to a pulpy mass; and in the third, 
its nutritive portions are taken up, to be conveyed into 
the circulating fluid. 

MASTICATION. 

138. The apparatus for masticating or dividing the food 
mechanically is found in accordance with the kind of food 

What is digestion? From what source is the food of plants obtained? 
How do animals derive their nourishment ? With what organs are all pro¬ 
vided ? In what animals are the digestive organs very simple ? What do 
ve find in the higher orders ? What is said in regard to the apparatus for 
masticating the food ? 



68 


CLASS-BOOK OF PHYSIOLOGY. 


which, the animal requires, and the rapidity with which 
the process of digestion is to be carried on. 

139. If the process of digestion is to be performed rap- | 
idly, the food requires division into small portions, so as | 
to present as large an amount of surface as possible to the | 
solvent fluid. Thus, in those animals which chew or mas¬ 
ticate their food most perfectly, the process of digestion 

is performed in a few hours; while in those which swallow 
their prey whole, as the snake, several days are required. ! 

140. The apparatus for masticating the food presents a 
great variety of forms, and is modified in the different 
orders of animals according to the kind of food on which 
the animal subsists; and yet it is so strictly in accordance 
with each animal’s organization, that an experienced anato¬ 
mist can tell, by the inspection of this apparatus alone, the 
class to which the individual belongs. 

141. Insects which masticate their food are furnished 
with jaws of a great variety of construction, and all admi¬ 
rably adapted for the service they are to perform. “Some 
are sharp, and armed with spines and branches for tearing j 
flesh; others are hooked, for seizing, and at the same time 
hollow, for suction. Some are like shears, for gnawing 
leaves, and others more like grindstones, of a strength 
and solidity sufficient to . reduce the hardest wood to 
powder.” 

142. Mastication, in most of the higher animals, is per¬ 
formed by means of teeth implanted in the jaws, and so 
arranged as to act against each other with a cutting, grind¬ 
ing, or chewing power, according to the nature of the food 
on which they operate. 

143. In man and most of the mammalia there are three 
kinds of teeth, namely, incisors , canine and molars. The 

How is the food divided when the process of digestion is performed rapidly ? 
How do the organs of mastication indicate the class to which each animal 
belongs? What is said of the jaws of insects? How is mastication per¬ 
formed in most of the higher animals ? How many kinds of teeth are there 
in man and the mammalia ? 





DIGESTION. 


69 


incisors have a thin cutting edge, intended simply to di¬ 
vide the food; the canine have a conical form, adapted to 
tearing it in pieces; the molars are formed for bruising 
or grinding the food. 

144. There are also two sets of teeth—the temporary or 
milk teeth , and the permanent teeth. 



Fig. 22. —Development of Teeth.— a, the Fig. 23. —Dental 

gum; b, the lower jaw; c, dental capsules. Capsule. 


145. The first set, or milk teeth , {fig. 22,) are twenty in 
number—four incisors in the front of each jaw, and two 
canine and four molar teeth on each side. All these teeth 
fall out at from six to eight years of age, and are gradu¬ 
ally replaced by the permanent teeth, {fig. 28,) which are 



Fig. 23— Human Teeth.— a, incisors ; b, canine tooth ; c, bicuspid teeth; d, molars. 

thirty-two in number, sixteen in each jaw, namely: four 
incisors, two canine, four bicuspids or small molars, and 
six true molars. The last molar does not make its appear¬ 
ance until long after the rest, and hence it is called the 
wisdom-tooth. 

146. The human teeth are composed of three distinct 

Describe each. How many sets of teeth are there ? How many teeth are 
there in the first set ? How many in the second 1 When does the last mo¬ 
lar make its appearance ? Of what are the human teeth composed ? 











70 


CLASS-BOOK OF PHYSIOLOGY. 


structures—the ivory or tooth-bone, the enamel , and the 
cementum. The ivory , which constitutes the main part of 
of the tooth, resembles bone in its structure, except it con¬ 
tains a larger amount of mineral matter, and is harder 
than bone. The enamel forms a crust oyer the whole sur¬ 
face of the crown of the tooth, and protects it from wear¬ 
ing out or decaying. It is composed of ninety-eight parts 
in a hundred of mineral matter, and is the hardest of all 
animal substances. The cementum forms a covering to 
the root of the tooth, and serves to make its attachment 
in the jaw more firm. Fig. 24 represents a section of a 
human tooth. 


Fig. 24.—Section of 
a Human Tooth.— 
d , dental cavity. 

147. Other animals have the enamel distributed differ¬ 
ently. The incisors of the rabbit and other rodentia or 
gnawing animals have the enamel on the front side of the 
tooth—the ivory being on the back part, is worn off first, 
leaving a sharp point of enamel, as represented in Jig. 25. 
The continual wearing away of the incisors in this class 
of animals is provided for by their constant growth from 
below. 

*148. In the horse, ox, and other grass-eating animals, 
the enamel forms upright plates in the midst of the ivory 
which forms the main body of the tooth. The ivory be¬ 
ing the softest, is worn away first, leaving the enamel in 

Describe each structure of the teeth. How is the enamel distributed on 
other animals'? Describe the incisors of a rabbit. Describe the teeth of 
grazing animals. What is said of the form of the teeth ? 









DIGESTION. 


71 


projecting ridges, which are admi¬ 
rably adapted to the grinding action 
of the tooth. {Fig. 26.) 

149. The particular form of the ^• 2C ~ TeethofHerbivorou “ 

. ,-i p . Animal. 

teeth ot any animal corresponds 
with the nature of the food on which that animal subsists. 
In those which live entirely on animal flesh, the molar 
teeth are so compressed as to form cutting edges, which 
work against each other like a pair of shears. {Fig. 27.) 
In animals which live on insects, the molar teeth are 
raised into conical points, which lock into corresponding 
depressions in the teeth of the opposite jaw, {Fig. 28.) 




Fig. 27.—Teeth of Carnivorous Fig. 28.—Teeth of Insect-eating 

Animals. Animals. 

When the animal lives on soft fruits, these teeth are sim¬ 
ply raised into rounded elevations. {Fig. 

29.) When they are destined to grind 
harder vegetable substances, their surface 
is flat and roughened, as in those of the 

horse and ox. Fig . 29.—Teeth of Frit- 

150. In fishes and reptiles, the teeth GIV0R0US an-mal. 
are short and bent backward, and are 
thus adapted to seizing and retaining 
their prey, rather than dividing or tear¬ 
ing it in pieces. The head of the rattle¬ 
snake is represented by fig. 80. In the 
front part of the upper jaw are two Fig ’ 30 * —Rattle ‘ Snake - 

What is the form of the teeth in animals which live on flesh?—on insects? 
—on fruits ? What is the form of the teeth in fishes and reptiles ? 










72 


CLA SS-BOOK OF PHYSIOLOGY 


poison fangs, consisting of hollow tubes, through which 
the poison secreted in the glands on each side of the head 
is injected. 

151. The teeth are brought into action by means of the 
muscles, which move the lower jaw in a manner corres¬ 
ponding with the nature of the food. In flesh-eating 
animals, the lower jaw has a hinge-like action, opening 
and shutting like a pair of shears, and the sharpness of the 
teeth renders them a powerful cutting instrument. The 
jaw of the herbivorous animals has a lateral motion, by 
which the food is ground between the rough surfaces of 
the teeth. In the gnawing animals, the lower jaw is 
drawn rapidly backward and forward, and the teeth are 
thus made to act as a powerful file, by which the hardest 
shell is quickly rasped to a powder. 

152. In man, we find a combination of each of the 
above movements. He can move the lower jaw upward 
and downward, from side to side, and forward and back¬ 
ward, and is thus adapted to the mastication of a mixed 
diet of all the endless variety of articles upon which he is 
accustomed to subsist. 


INSALIVATION. 



153. Insalivation is the act of blending with the food 
the saliva, which is a watery fluid secreted in the parotid, 
sublingual and submaxillary glands, and poured into the 
mouth during the process of mastication. The parotid 
glands are situated on each side of the cheek, just below 
the ear; the sublingual, under the tongue; and the sub¬ 
maxillary, near the angles of the lower jaw. 

154. The use of the saliva is to make the food soft and 
moist, so that it can be more easily swallowed, and be 
rendered more solvent in the digestive fluid of the stomach. 


How are the teeth brought into action? How does the lower jaw act in 
different animals? Describe the movements of the lower jaw in man. What 
is insalivation ? Where are the salivary glands situated ? What is the use of 
the saliva ? 




DIGESTION. 


73 


When the organs of mastication are at rest, only saliva 
enough is secreted to keep the mouth moist; but its flow 
is greatly increased when the movements of mastication 
commence, and when food is taken into the mouth. The 
sight or even the thought of food will frequently cause 
the saliva to be poured out more freely, making “the 
mouth water,” as it is termed. During the progress of 
fever, the secretion of saliva ceases or is very much dimin¬ 
ished, and the mouth becomes dry and parched. 

155. If the food is imperfectly masticated, or is swal¬ 
lowed very rapidly, the saliva is also imperfectly mixed 
with the food, and the work of digestion becomes corres¬ 
pondingly more difficult. In this country, impaired diges¬ 
tion and loss of general health is a frequent result of 
rapid eating. 

156. When mastication has 
been completed, the food is trans¬ 
mitted in successive portions to 
the stomach by the act of degluti¬ 
tion or swallowing. The food is 
first collected into a ball or mass 
by the action of the muscles of 
the cheeks and tongue, and is 
conveyed back against a sort of 
movable curtain (the vail of the 
palate), which hangs from the 
sides of the palate so as to touch 
the tongue by its lower border, 
and makes the mouth a closed 
cavity. {Fig. 31.) The instant 
the food is brought against this 
partition, it opens, and allows the 
food to pass into the pharynx. 

The oesophagus or food-pipe receives the morsel from the 

When is the saliva secreted ] How is the secretion of saliva affected by 
fevers 1 How is digestion affected by an imperfect mastication of the food ? 
How is the food transmitted to the stomach 1 
6 






74 


CLASS-BOOK OF PHYSIOLOGY. 


pharynx, and forces it along to the stomach by the alternate 
contraction of its successive portions. The undulating 
movement produced by the contractions may be readily 
observed in the oesophagus of a horse while in the act of 
.drinking. 

/ 157. The form and size of the stomach varies in differ¬ 
ent animals, according to the nature of the food to be 
digested. It is found in its simplest condition in the class 
of polypes,of which the hydra (fig . 14) is an example. In 
this animal, the stomach is merely a bag or sac with one 
opening, as represented in fig. 4, Pl. VII. Around this 
orifice to the stomach are from six to ten arms, for the 
purpose of seizing its prey, which is swallowed whole, and 
readily digested without any mechanical division what¬ 
ever. In the planaria, (fig. 1, Pl. VII.) an animal of a 
little higher organization, numerous branches or canals 
pass off from the stomach to various parts of the body. 

158. In all the higher orders, the stomach has two ori¬ 
fices, and is prolonged into a canal, as represented in fig. 5, 
Pl. VII., called the alimentary canal. In the carnivorous 
animals, whose food is flesh, which is easily dissolved, the 
stomach is very simple in its structure, and the alimentary 
canal comparatively short. 

159. The most complex stomach and the greatest length 
of alimentary canal is found in ruminating animals—as the 
ox, sheep, deer, &c. In this class of animals, the stomach 
possesses four distinct cavities, as represented in fig. 82, 
which represents the stomach of a sheep. The food is at 
first imperfectly masticated in the mouth, and passed to 
the first stomach, to be macerated; it is then passed into 
the second stomach, where the fluids are received, and 

What is said of the form and size of the stomach ? In what class of ani¬ 
mals is it found in its simplest condition ? Describe the stomach .of a hydra. 
What variation is found in the planaria 1 ? Describe the stomach of the higher 
orders of animals. In what class of animals is the stomach the most com¬ 
plex ? How many cavities are there in the stomach of a ruminating animal 1 
Describe the course of the food through the several cavities. 























































































































' 

























































1 


I 


ORGANS OF DIGESTION. 


PLATE VII. 



Figure 1. - Digestive Apparatus of a Planaria. — a, Mouth, surrounded by a circulai 

sucker, b , Buccal cavity, c, Orifice of the oesophagus, d, Stomach, e, Ramifications 
of gastric canals. /, Cephalic ganglia and their filaments. > 

Figure 2.- Digestive Apparatus of a Fowl. — a , (Esophagus, b, Crop, c, Second 

stomach, in which the gastric juice is secreted, d, Gizzard, c, Liver. /, Gall-bladder. 
g , Bile ducts, /t, Pancreas, t, Duodenum, /c, Large intestine—its two caeca, l. 

Fioure 3.- Digestive Apparatus of a Beetle —a, The head and jaws, fi, Crop, c, 

The gizzard, d, The true digestive stomach, surrounded by its follicles, e, The long ves¬ 
sels which constitute a rudimentary liver. 

Figure 4. - Ideal Representation of the Simplest Form of a Stomach , as found in the 

hydra. 

Figure 5. - Ideal View of the Alimentary Canal , as found in the higher orders of 

animals. 










no 


PL V]J 



•0 n r. 


Kellogg Lith 










































































DIGESTION. 


79 


rolled into a small ball, to be returned to the mouth, and 
undergo a second process of mastication, called “chew¬ 
ing the cud.” When the food is again swallowed, it is 
passed into the third and thence into the fourth stomach 
to go through the final process of digestion. 

(Esophagus 

Oardia 
3d Stom. 


Intestine 

Pylorus. 4th Stom. 2d Stom. 1st Stom. 

Fig . 32.—Stomach of the Sheep. 

160. Birds, which have no means of masticating theii 
food, are provided with a peculiar modification of the 
stomach. In those which live on grain—as the common 
fowl, quail, &c.—the food is first moistened and softened 
in the crop, just as it is in the first stomach of the sheep. 
It is then passed through a second stomach (where it is 
saturated with the gastric juice) into the gizzard. In the 
gizzard, it undergoes a triturating or grinding process, 
which is accomplished by means of pieces of quartz or 
other angular stones, which the bird instinctively swal¬ 
lows for the purpose, and the strong muscular action 
of the organ. The digestive apparatus of a fowl is repre¬ 
sented in fig. 2, Pl. YII. 

161. A powerful gizzard is also found in most insects, 
but it is placed above the digestive stomach instead of be¬ 
low it, as in birds. In fig. 3, Pl. YII., is represented the 
digestive apparatus of a carnivorous beetle. 

How ia the stomach modified in birds? How is the gizzard placed ia 
insects ? 











80 


CLASS-BOOK OF PHYSIOLOGY. 


162. By a comparative view of the structure of the 
stomach in the different groups, we cannot fail to observe , 
a regular gradation, from the simple digestive sac of the , 
hydra to the complex apparatus of the ruminating animals. 
In man, the stomach is intermediate between the carniv¬ 
orous and herbivorous mammalia, and is very clearly 
adapted to a mixed diet. 

163. The stomach in man is an oblong membranous bag, 
placed obliquely across the abdomen, and just below the 
diaphragm. Its average capacity in the adult is about 
one quart, though it may be distended to contain a much 
larger quantity, or be contracted to a very small size. 

It has two open¬ 
ings—one towards 
the heart, called 
the cardiac orifice , 
which receives the 
food from the oeso¬ 
phagus—and the 
other at the right 
or small end of the 
stomach,called the 
pyloric orifice , for 
the transmission 
of food to the small 
intestines. The 

Fig. 33.—A Section of the Stomach.— a, the oesophagus; n n .i 

b, the cardiac orifice ; c, the great end of the stomach ; d, its IOTO1 01 tile StOm- 
lesser or pyloric end; d% the pyloric orifice; e, the lesser v n 
curve; /, the greater curve; g, the rugae or wrinkles of the «Cn an Cl tile pOSl- 
mucous membrane; A, the pylorous; i,j, the duodenum,r» •. 
or first portion of the small intestine; A, the duct through W-On OI IIS Open- 

duodenum. “ d panorealic iuice are poure ‘ l ,he ings are represent- 

ed in fig. 33. 

164. The stomach possesses three coats—the outer or 
serous , the middle or muscular , and the inner or mucous 
coats. 

What do we observe by a comparative view of the stomach in different 
animals? Describe the human stomach. How is it placed? What is its 
average capacity in the adult ? How many openings has it, and what are they 
called? How many coats does the stomach possess, and what are they? 






DIGESTION. 


81 


165. The serous coat is the same as the external coat of 
all the organs which are not exposed to the air. Its use 
is to secrete a fluid which lubricates the surface of the 
organs, and prevents friction between them. 

166. The muscular coat is composed of numerous mus¬ 
cular fibres, such as we see in lean meat. These fibres 
possess great power of contraction, being drawn up and 
stretched out again like India-rubber without injury. 
Some of these fibres run lengthwise of the organ, some 
wind around it in the form of rings, and others run ob¬ 
liquely across it. By the alternate contracting and relaxing 
of these fibres, a great variety of motion is produced during 
the process of digestion, causing the food to be rolled 
about and moved successively over every portion of the 
inner or mucous coat. In the act of vomiting, there is a 
spasmodic contraction of all the fibres, throwing the con¬ 
tents of the stomach back into the mouth. 

167. The mucous membrane (Jig. 84) 
lines the inside of the stomach with a 
very soft and velvety investment. It is 
not elastic, like the other coats, but is 
drawn into folds when the stomach is 
contracted, and spreads out smoothly 
when it is dilated. This coat secretes 
mucous or slimy matter, which protects 

the stomach from being unduly irritated tomofeafh. natthebot " 
by its contents, and it also pours out 
from numerous little follicles or glands the gastric juice, in 
which the food is dissolved. 

168. The gastric follicles perform an important part in 
the process of digestion. They are of a tubular form, as 
represented in fig. 35, from ^-loth to a^th of an inch in 
diameter. When there is no food in the stomach, these 



Describe the serous coat of the stomach—the muscular coat—the mucous 
coat. What does the mucous coat secrete 1 What is secreted by the gastric 
follicles ? What is the use of the gastric juice 1 Describe these follicles. 







82 


CLASS-BOOK OF PHYSIOLOGY. 


follicles or glands are at rest; but imme¬ 
diately on the introduction of food, they 
commence secreting actively an acid fluid, 
which exudes in drops, running down the 
walls of the stomach, and soaks into the 
substances within it. 

169. The gastric-fluid is a very powerful 
solvent of all proper food of every kind, 
whether animal or vegetable. It is indis¬ 
pensable to digestion, and is found no 
where but in the living stomach. 

170. The amount of gastric fluid se¬ 
creted at one time, corresponds with the 

Fifr. 35.—onk of quantity of food which is then needed by 

Tubular Follicles - _ ^ . . T .. . J 

of the stomach, the body as nourishment. It begins to 
flow as soon as the first mouthful of food 
is introduced into the stomach, and continues to be poured 
out till the demand for nourishment is supplied, and then 
ceases. If more food be taken than is sufficient for the 
wants of the system, it will remain undigested, and be¬ 
come a source of irritation and oppression; or, being 
mixed with that previously received into the stomach, the 
digestion of the whole is retarded. 

171. The sense of hunger is felt when there is a demand 
for a fresh supply of nourishment, and the stomach is in 
a condition to pour out its secretion, If the food be then 
swallowed no faster than the gastric fluid is prepared to be 
mixed with it, hunger or the desire for food will cease 
when the secretion ceases, or when just food enough has 
been taken; but if the food be swallowed twice as fast as 
it can be supplied with gastric juice, the sense of hunger 
will continue till twice as much is taken as is actually re- 

How does the gastric juice act on all k.nds of food? With what does the 
amount of gastric juice correspond? When is it secreted ? How is the food 
disposed of when more is taken than is required ? When is the sense of 
hunger experienced? When does it cease to be felt? What is the conse¬ 
quence of swallowing the food twice as fast as it should be? 








DIGESTION. 


83 


quired. Hence, rapid eating creates an unnatural appetite, 
frequently causing nervous irritability, and dyspepsia or 
disease of the stomach. In this country, where men are 
governed more by the excitement of .business than by any 
regard to health, rapid eating is a prevailing sin, the con¬ 
sequences of which are apparent in a greater proportion 
of dyspeptic complaints than are to be found in any other 
country. 

172. When the proper kind of food has been taken in 
proper quantities, the fibres of the muscular coat of the 
stomach alternately contract, pressing the mass of food 
backward and forward , and from side to side, exposing 
every part of it to the action of the gastric juice, until its 
solution is complete. This process lasts from two to five 
hours, or even logger, according to the kind of food and 
the thoroughness with which it has been masticated. The 
agitation of the food is assisted by the action of the respir¬ 
atory organs, in alternately raising and depressing the 
diaphragm whenever the air is inhaled or exhaled from 
the lungs. 

173. “The readiness with which the gastric fluid acts 
upon the several articles of food is in some measure deter¬ 
mined by the minuteness of division, and the tenderness 
and the moisture of the substance presented to it. By 
minute divisions of the food, the extent of surface with 
which the digestive fluid can come in contact is increased, 
and its action proportibnably accelerated.” Hence, when 
the food is thoroughly masticated, it digests with greater 
facility. Tender and moist substances also digest more 
easily than those that are tough, hard, and dry; because 
they are more easily as well as more thoroughly penetrated 
by the gastric fluid. 

174. The value of any particular substance, as an article 

What evils result from rapid eating? Describe the manner in which the 
food is moved backward and forward in the stomach. How long does thi 
process last? What circumstances facilitate the action of the gastric juice o.. 
»he food? 



84 


CLASS-BOOK OF PHYSIOLOGY. 


of diet, is not in all cases in proportion to its digestibility; ;> 
for many substances tliat are easily soluble in the gastric 
fluid afford only a small amount of nourishment, while , 
others that are more difficult of solution are highly nutri¬ 
tious. Fresh fish, for instance, may be digested in less | 
than half the time required for beef-steak, though the beef- 1 
steak is decidedly the most nutritious. A substance, to be 
nutritive^ must not only contain an abundance of those 
elements which go to form the tissues of the body, but it 
must be capable of being digested by the gastric fluid or 
some other secretion in the alimentary canal, and of being 
assimilated to the blood. 

175. When digestion is completed in the stomach, the 
food and gastric juice are thoroughly mixed, and converted 
into a pulpy mass, called chyme. There are many circum¬ 
stances, besides the nature of the food, which affect this 
process. 

176. Only a sufficient quantity of food should be taken 
to fairly fill the stomach, and not to distend it. 

177. Sufficient time should elapse after each meal to 
allow the stomach to become empty before a fresh supply 
is taken. This interval in adults should generally be five 
or six hours, though it varies with the kind of food, the | 
condition of the stomach, and the constitutional peculiari¬ 
ties of each individual. In young persons, where all the 
functions are performed with more activity and vigor, the 
intervals between the meals may be much shorter than 
in adults. 

178. Gentle exercise, both before and after each meal, 
is favorable to digestion; while excessive exertion, whether 
bodily or mental, retards it. 

Is the value of a particular article of diet in proportion to its digestibility ! 
What properties do render an article of diet nutritive ? What is the food 
converted into when digestion is complete ? What should be the quantity of 
the food 1 ? What time should be allowed between each meal 1 ? Why should 
the intervals between the meals be shorter with young persons than with 
adults? How does exercise affect digestion? 





























































































CT 





















PLATE VIII. 


n -r 
iULL - 


ORGANS OF DIGESTION. 


Figure 1.- General View of the Digestive Organs of Man. —This figure is intended 

to give n general idea of the forms and relative positions of the organs of digestion.— a, 
The oesophagus. A, The stpmach. c, The duodenum, d, d, d, Convolutions of the small 
Intestine, e, The ccecum. f, Appendix of the ccecum. g, Opening of the small into tho 
large intestine. A, The ascending colon, i, i, Transverse arch of the colon, j, The de¬ 
scending colon. A, The liver. /, The gall-bladder, m, The pancreas, mostly covered by 
the stomach, o, The spleen.—In this figure, the liver is raised up and the transverse arch 
of the colon drawn down, in order to show parts which they cover when in their natural 
situation. 

Figure 2.- General Aspect of the Abdominal Viscera. —In this figure, the anterioi 

walls of the abdomen are removed, so as to show the organs in their natural positions. 
The small intestine is removed.— a , The liver, situated beneath the right arch of the dia¬ 
phragm. A, The stomach, c, Epiploa, or floating folds of the peritoneum. <£, Summit 
of the gall-bladder, e, e, Large intestine, showing all its courses. 

Figure 3. - The Chyle-Vessels and the Thoracic Duct. —a, A portion of the small 

intestine. A, A, Origins of lacteals. c, Mesentery, d, Mesenteric glands, c, Lymphatic 
vessels. /, Thoracic duct, g, Aorta, h , Thoracic duct, curving downward and forward, 
to empty its chyle at the junctions of the left jugular and sub-clavian veins. 

Figure 4.- The Pancreas. —This figure is given to show more clearly the situation 

and connexions of the pancreas, a, The pancreas. A, The duodenum, c, The gall-blad¬ 
der. <Z, Duct of tho gall-bladder, which communicates with the hepatic duct, e, which 
leads from the liver. /, Duct of the pancreas, which opens into the common bile-duct, g y 
through which the combined secretions of the pancreas and the liver are poured into the 
duodenum. 

Figure 5. - The Liver. —Section of the liver, showing the ramifications of the vessels. 

The hepatic vena portae is a division of the abdominal vena portae, into which empty all 
the veins of the digestive organs. It sends branches into all parts of the liver. After 
these branches have reached the capillary state, they are succeeded by the roots of tho 
hepatic veins, which unite into three large veins which empty into the inferior vena cava. 
a , The right or greater lobe. A, The left or smaller lobe, c, Groove which lodges tho 
umbilical vein, d, Hepatic vena portae, e , Hepatic artery. /, Inferior vena cava. 

Figures 6 and 7.- Liver. —Figure C represents a horizontal section of two superficial 

lobules of the liver, showing the probable arrangement of the biliary ducts, o, a, Inter 
lobular branches of the hepatic veins. A, A, Trunk of biliary ducts. 

Figure 7 represents a horizontal section of three superficial lobules, showing the two 
principal systems of blood-vessels, a, n, Inter-lobular veins proceeding from the hepatic 
veins. A, A, Inter-lobular plexuses formed by brunches of the portal veins. 







pi mu 




MS 


,■' :■'> ,'/^fpTTTl', 


Hartford, Conn 



































































































































































DIGESTION. 


89 


179. A quiet and tranquil state of mind is also essential 
to good digestion. 

180. Drinks taken in large quantities materially inter* 
fere with the process of digestion. The juices secreted by 
the stomach itself are sufficient for the solution of most 
articles of diet; and whenever a superabundance of liquid 
is swallowed, the first effort of the stomach is to get rid 
of it. This it does by absorbing the liquid at once and 
without change through the blood-vessels of the mucous 
coat. The digestion of the more solid materials is not 
commenced until the liquid is disposed of. 

181. As soon as any portions of the food become suffi¬ 
ciently digested to mix with the gastric fluid, and form 
chyme, they are sent through the pyloric orifice of the 
stomach into the duodenum, or first portion of the aliment¬ 
ary canal. {Fig. 33.) Around the pyloric orifice {d), at 
the inside, is a thick band or valve, called sphincter. 
When digestion is not going on, this sphincter, as well as 
a similar one at the cardiac orifice {b ), is so completely 
closed that none of the contents of the stomach can escape. 
But towards the termination of the digestive process, the 
pylorus offers less resistance. First it yields to allow the 
successively digested portions to go through it, and after¬ 
wards it allows the passage of even undigested portions, 
which are always retained in the stomach much longer 
than those portions that are readily digested, and produce 
the irritability and suffering so often experienced after eat¬ 
ing indigestible substances. 

182. In the intestinal or alimentary canal the food is 
further acted upon, and undergoes other changes. 

183. The alimentary canal is divided into two portions, 
named, from their difference in diameter, the small and the 

What effect has the mind on digestion? How do drinks affect digestion 
when taken in large quantities? How does the stomach get rid of the fluids? 
What course does the food take when it has become sufficiently digested to 
form chyme? Describe the pyloric orifice of the stomach. Into how many 
pcrtions is the alimentary canal divided? 




90 


CLASS-BOOK OF PHYSIOLOGY. 


large intestines. This distinction is much less marked in 1 
carnivorous animals than in those which, feed on vegeta- : 
bles, and the length of the canal differs greatly in the two 
orders. In the tiger, for instance, the intestines are about 
three times the length of the body. In the sheep, they 
are about twenty-eight times longer than the body, or 
seven times as long as those of the tiger in proportion to 
the size of the animal. In those animals which live on a 
mixed diet, the intestines are of a medium length. In j 
man, they are about six times the length of the body. 

184. The small intestine, which commences at the pyloric j 
orifice of the stomach and terminates in the large intes¬ 
tine, is about twenty-five feet in length in man, is a narrow 
tube with thin walls, and is coiled in various directions, , 
as represented at d, fig. 1, Pl. YIII. 

185. The large intestine, or colon, is about five feet in 
length, and resembles in appearance a long sac divided into 
numerous pouches. 

186. The intestines, like the stomach, have three coats— | 
the peritoneal or serous, the muscular, and the mucous. I 
The mucous membrane of the small intestine is found in 
transverse folds, which greatly increase the extent of its 
surface. 


187. In the substance of the mucous 
membrane, glands are imbedded, one of 
which is represented in fig. 86, and the 
surface is studded with minute process¬ 
es, termed villi. 

188 * Through these villi the nutritive 
•Single gland of portion of the digested food is absorbed, 
and conveyed by a set of vessels, called 
lacteals , into the general circulation. 

189. After the chyme or digested food has passed out 



Fig, 36. 

SMALL INTESTINE. 


What is the length of the alimentary canal in the tiger?—in the sheep?_ 

in man ? Describe the small intestine—the large intestine. How many coats 
have the intestines? What glands are imbedded in the mucous membrane of 
the intestine ? 





DIGESTION. 


91 


of the stomach into the small intestine, it becomes mixed 
with the bile secreted bj the liver, and with the juice se¬ 
creted by the pancreas or sweet-bread. 

190. The pancreas is a long narrow gland, situated partly 
behind the right side of the stomach, and within the first 
curve of the small intestine, as represented at m, fig. 1, 
Pl. YIII. The fluid which it secretes seems to be of a 
nearly similar nature with saliva, and is supposed to assist 
in digesting fatty substances, and rendering them fit for 
absorption. 

191. The liver is the largest gland in the body. It is 
situated in the right side, below and in contact with the 
diaphragm, and is divided into several lobes. At its lower 
side is the gall-bladder, into which the bile is poured, after 
being secreted. The gall-bladder thus serves as a reser¬ 
voir to the bile. Its duct opens into a duct leading direct 
from the liver, and forms with it the common bile-duct, 
through which the bile is poured into the small intestine 
at the same point with the duct from the pancreas. These 
ducts are represented in fig. 4, Pl. YIII. 

192. The bile is a greenish-yellow fluid, having an ex¬ 
tremely bitter taste and a nauseous smell. It is constantly 
secreted by the liver; but, during fasting, it accumulates 
in the gall-bladder, whence it is poured out on the intro¬ 
duction of food into the stomach. 

193. By the mingling of bile and pancreatic juice with 
the chyme in the small intestines, chyle is formed. The 
chyle is a whitish milk-like fluid, with a somewhat saltish 
taste. It is, in fact, imperfectly-formed blood, and nearly 
resembles blood in its constituent parts. The chyle is ab¬ 
sorbed as the digested food passes along through the small 
intestine. The residue of the chyme, consisting of indi- 

What changes does the food undergo after passing out of the stomach? 
Describe the pancreas. What is supposed to be the use of the fluid secreted 
by the pancreas? Describe the liver. How is the gall-bladder situated? 
What are the properties of the bile? How is the chyle formed? How is it 
absorbed ? 


92 


CLASS-BOOK OF PHYSIOLOGY. 


gestible substances, gradually becomes more and more dry 
and bard, till it is at length carried into the large intestine, I 
and thence excreted from the system. 

194. The food and the several secretions mixed with it ! 
are carried through the intestinal canal, and slowly exposed j 
to the action of the absorbent vessels by the peristaltic or 
vermicular movements of the intestines. This movement 
is effected by means of the successive contractions and 
dilations of the intestinal coats, which extend in a wave¬ 
like manner throughout the tube. In health, this move¬ 
ment is slow, and generally unperceived by the mind; but 
it becomes very perceptible in diarrhea, or when acceler 
ated by the influence of purgatives. 

195. The natural movements of the bowels are indis¬ 
pensable to the continuance of health, and they should not 
be restrained by tight waist-bands or ligatures around the 
body. The habit of wearing garments that are too tight 
is a frequent cause of inactive or constipated bowels, and 
finally leads to impaired health and disease. 


What movements force the passage of the food along the alimentary canal't 
What effect does the wearing of tight garments have on the natural move¬ 
ments of the bowels and on health? 



ABSORPTION. 


93 


CHAPTER VII. 

ABSORPTION. 

196. Absorption is that process bj which all the various 
elements of the body are taken into the circulation. 

197. All the tissues of the body, except the enamel of 
the teeth, and some of very low organization, as the hair 
and nails, possess to some degree the power of absorption. 

198. Fluids are absorbed most readily, and none are 
absorbed with so great facility as water. A large propor¬ 
tion of the weight of the body is due to the water which 
its tissues absorb. Muscle, in drying, loses three-fourths 
of its weight, and blood four-fifths. Mummies have been 
found of adult size with all the organs entire, but reduced, 
by the evaporation of the watery fluids, to a weight not 
exceeding eight pounds. 

199. The process of absorption is performed throughout 
all the tissues by two sets of vessels, viz: the lymphatics 
or ladeals and blood-vessels. 

200. The lymphatics —a portion of whiSh are also lac- 
teals —constitute a peculiar and distinct system of vessels, 
which are distributed to every part of the body where 
there are blood-vessels. The lymphatics derive their name 
from the peculiar limpid fluid or lymph which they convey. 

201. Those which have their origin in the mucous mem¬ 
brane of the alimentary canal have received the name of 
lacteals, from the milky appearance of the chyle which 
they absorb. 

202. The lymphatics are minute and delicate vessels, 
with walls so thin that they are nearly invisible unless 

What is absorption ? What tissues possess the power of absorption ? To 
what i3 a large portion of the weight owing? How much of its weight does 
muscle lose in drying 7 —and blood, how much ? To how small a weight have 
mummies been found reduced ? By what vessels is the process of absorption 
performed? What are the lymphatics? From what do lymphatics derive 
their name ? What are the lymphatics called that have their origin in the 
mucous membrane ? Describe the lymphatics. 

7* 



94 


CLASS-BOOK OF PHYSIOLOGY. 


distended with some colored substance. They commence 
in closely meshed net-work, or in loops distributed upon 
the external surface of all the organs, and interspersed 
among the proper elements and blood-vessels of all the 
several tissues. 

203. Externally the lymphatics present a 
constricted or knotted appearance, owing to 
ng. 37 .-lymphatics. the existence of numerous valves, formed 
by semi-circular folds of the lining membrane, arranged 
in pairs, {fig, 37,) and their edges coming together so 
as to prevent the flow of fluids, except in the direction 
towards the heart. By this arrangement, all muscular or 
external pressure accelerates the flow of lymph, as'it does 
that of the blood in the veins. In reptiles and some birds 
the flow of the lymph is effected by muscular sacs, called 
lymph-hearts. 

204. The lymphatic glands are small, oval, and some¬ 
what flattened or rounded bodies, composed of a plexus 
of minute lymphatic vessels, and a plexus of blood-ves* 
sels convoluted or twisted upon each other, and inclosed 
in a thin cellular capsule, in such a manner as to form small 
knots or kernels, as they are sometimes called, when they 
become inflamed and swollen. In scrofulous persons, these 
glands are exceedingly liable to become enlarged, particu¬ 
larly on the sides of the neck and in the armpits. 

205. The contents of the lymphatics pass through the 
lymphatic glands, and undergo a process of digestion, by 
which they are renovated and fitted for further use in the 
animal economy. 

206. The lacteals , or lymphatics of the alimentary canal, 
commence in the villi of the mucous membrane, as repre- 

How do th<?y commence 1 What is the appearance of the lymphatics 
externally 1 How are the valves formed ? Of what use are the valves ? 
How is the flow of lymph effected in reptiles ? What are lymphatic glands 1 
What are they sometimes called when they become inflamed 1 How are the 
contents of the lymphatics affected by passing through these glands ? How 
do the lacteals commence ? 





ABSORPTION. 


95 



sented in fig. 38. 

Each villus resem¬ 
bles in appearance 
a minute papilla 
or point in the mu¬ 
cous membrane, 
and is formed of an 
extremely delicate 
membrane,termed 
epithelium which 
contains a plexus 
of lacteals, all 
forming a fine net¬ 
work in the sub¬ 
mucous tissue, {fig. 

39.) Each villus sends forth only 
one lacteal vessel, and this so small 
as to be imperceptible to the naked 
eye. 

207. As the lacteals issue from the 
villi, they unite to form large trunks, 
and, passing through the mesenteric g 
glands, join in one common trunk the |j|^^ ^ 
thoracic duct , and may thus be com- 


Fig. 38— Diagram of Mucous Membrane.— A, 
intervals of digestion; B, during digestion; a, a, i. 
ent vessels; ft, ft, absorbent cells of a villus; c, c, 
follicles between the villi. 



pared to the roots of a tree, which Fig. 39.— Appearance of Lym¬ 
phatics IN THE MUCOUS MEM¬ 
BRANE OF THE STOMACH.—ffl, 

superficial layer; ft, deep layer. 

main trunk, the body of the tree. 

208. The thoracic duct is the main trunk, into which the 
contents of the lymphatics and lacteals are emptied. It 
commences in front of the second lumbar vertebra, and 
passes up in front of the back-bone to discharge its con¬ 
tents by a valvular opening into the large vein just beneath 
the clavicle or collar-bone. 


commence in numberless minute fibres 
in the soil, and finally join to form its 


' Describe a villus. What do the lacteals unite to form ? Through.what 
glands do the lacteals pass ? Describe the thoracic duct. Into what does the 
thoracic duct discharge its contents? 














96 


CLASS-BOOK OF PHYSIOLOGY. 


209. Absorption by lymphatics or lacteals takes place 
through the walls or coats of the vessels, and these are so 
constituted that only those materials which are suited to 
form lymph and chyle can traverse them. This system 
of vessels therefore possesses the remarkable property of 
selecting those elements which are in a state of organiza¬ 
tion to fulfil certain specific purposes in the animal economy, 
and all others are rejected. Hence, the lymph and chyle 
invariably present nearly the same characteristics and 
contain the same elements. 

210. But blood-vessels do not seem to possess any such 
power of selecting materials as has been attributed to lym¬ 
phatics and lacteals; for any substance, whether gaseous, 
liquid, or a soluble, or a minutely divided solid, may be 
absorbed by a blood-vessel provided it is capable of per¬ 
meating its walls. 

211. In the alimentary canal, the fluids are taken up by 
the veins, and the more solid materials by the iacteals. 

212. From the skin, absorption is performed mainly by 
the veins, though it is a well-known fact that various poi¬ 
sonous and medicinal substances take effect through the 
lymphatics. When irritating substances are rubbed on the 
skin, red streaks soon appear in the course of the lym¬ 
phatics, and the lymphatic glands become swollen and in¬ 
flamed. In like manner, poisonous substances acquired 
through slight wounds, such as are received in dissecting 
dead bodies in a certain state of decomposition, or by the 
sting of insects or by the bite of reptiles, extend along the 
course of these, and produce fatal consequences. 

213. There are peculiar conditions of the body in which 


How does absorption by lymphatics or lacteals take place ? What materials 
can traverse the walls of the lymphatics ? What remarkable property does 
this system of vessels possess? Do blood-vessels possess any power of select 
ing materials? What substances maybe absorbed by blood-vessels? How 
are substances taken up in the alimentary canal ? How is absorption per 
formed from the skin ? How are poisons known to take effect ? Under wlia 
circumstances does absorption from the skin take place wi'h great activity? 


ABSORPTION. 


97 


tlie absorption of fluids through the skin is performed with 
very great activity. Persons who are suffering from thirst, 
receive great relief by applying water to the skin. When 
the natural amount of fluids in the body has been dimin¬ 
ished by excessive perspiration, or by long abstinence 
from fluids, the weight of the body may be increased 
several ounces or pounds by immersion in a warm bath. 

214. It is on account of the increased activity of the 
absorbents that contagious disease is acquired more easily 
after fasting than after a full meal. Fear, anxiety of 
mind, as well as every thing that depresses the tone and 
vigor of the system, renders it more susceptible to dis¬ 
ease through the increased activity of the absorbents. 
Hence, epidemics that are propagated by an impure state 
of the atmosphere are most fatal among those who have 
the most dread of disease, and thus a quiet mind and an 
easy conscience are the best safeguards against contagious 
disease. 

215. The necessity for a constant supply of food arises 
from the continual decomposition which is taking place in 
the living body. By this process, materials for nutrition 
are all the while set free, which it is the special office of 
the lymphatics to take up and pass through a kind of 
second digestion, thereby fitting them for further use in 
forming the tissues of the body. By this process of inter¬ 
stitial absorption, animals may live for a long time on 
their own solids. Hibernating animals, for instance, which 
retire to their winter-quarters loaded with fat, gradually 
become lean, and spend from four to five months of the 
year with no supply of nutriment, except such as is 


Why are contagious diseases acquired more easily after fasting than after 
a full meal? What causes render the system more susceptible to disease? 
Among what class of persons are epidemics most fatal ? What are the besl 
safeguards against contagious diseases? What creates a necessity for a con¬ 
stant supply of food ? What materials are taken up by the lymphatics? How 
may animals live for a long time on their own solids? What is said in regard 
to hybernating animals? 




98 


CLASS BOOK OF PHYSIOLOGY. 


derived from the enormous quantities of fat which they 
lay in store during the period of their activity. 

216. The mucous membrane is the most important 
channel through which all the new materials for the nour¬ 
ishment and growth of the body are introduced. The 
more nutritive portions are taken up chiefly by the lac- 
teals, while liquids are absorbed by the veins. 

217. In the lowest tribes of animals, and in the earliest 
condition of the higher groups, absorption by the skin 
seems equally important to the maintenance of life with 
that which takes place from the digestive cavity. 


CHAPTER VIII. 

NUTRITION. 

218. Nutrition is that vital process by which the aliment¬ 
ary materials are converted into organized tissue. It consists 
essentially in a deposition in each tissue of the body of those 
elements which maintain its life and growth. 

219. It is the function of the digestive organs to prepare 
from the food the elements of nutrition. By the process 
of absorption, they are taken from the digestive cavity, 
and emptied through the thoracic duct into the large vein, 
and thence into the right side of the heart, to be passed 
through the lungs into the left side, and from thence dis¬ 
tributed by the arteries to all parts of the body. 

220. The peculiar process by which the nutritive ele¬ 
ments of arterial blood are formed into tissues, is called 
nutrition. But it is very evident that this process is 
dependent for its perfection upon other circumstances. 
There must not only be an abundant supply of nutritive 

Through what channel are the materials for the nourishment and growth 
of the body chiefly taken up? What portions are taken up by the lacteals, 
and what by the veins? What is said in regard to absorption by the skin? 
What is nutrition? In what does nutrition essentially consist? By what 
organs are the elements of nutrition prepared ? How are the elements of 
nutrition taken up? What circumstances maybe regarded as essential to 
nutrition ? 




NUTRITION. 


99 


food, but the food must be well digested; the absorbents 
must transfer its nutritive portions to the general circula¬ 
tion. The heart and lungs must also perform their functions 
properly. If there is a failure in any of these particulars, 
the body cannot be perfectly nourished. Hence, it not 
unfrequently happens that the causes of deficient nutrition 
are not easily comprehended. Appetite, digestion, absorp¬ 
tion, respiration, and circulation, may all be regarded as 
indispensable to a healthy nutrition. 

221. The tissues of the body are constantly undergoing 
a series of rapid changes, in which the particles are decom¬ 
posed and removed, to be replaced by new ones, which in 
their turn die and pass away. Yet every atom removed 
is supplied with a new one, so perfectly resembling the 
original, that the identity of an adult person is maintained 
through a series of years with the same form, size, and 
features, and in many instances the same weight, when 
perhaps not a particle of the original matter that consti¬ 
tuted his body is retained. Each part and organ exactly 
maintains its form and composition during the successive 
changes of many years. 

222. Each individual particle or atom has its own 
period of life, which is long or short according to the 
character of the tissue in which it is found. In muscle, 

| for instance, it is supposed the changes are much more 
frequent than in bone. The milk-teeth exist for a limited 
period, and are then partially absorbed, and fall out, to be 
replaced by a more permanent set. The hair of quad¬ 
rupeds, the feathers of birds, and the antlers of deer, are 
shed and reproduced annually with nearly the same form, 
color, &c. 

223. It is supposed that every action of any of the parts 
of the body is attended with a change of particles. When 

What changes are the tissues constantly undergoing? How are the par¬ 
ticles removed from the body supplied ? What is said of the life of each 
individual particle ? In what tissue are the changes the most frequent ? What 
takes place with every action of any part of the body? 




100 


CLASS-BOOK OF PHYSIOLOGY. 


we move an arm, for instance, some of the atoms in the 
muscles which produce the motion die, and leave their 
places, being replaced bj others. 

224. The rapidity of the changes may also be supposed 
to be in proportion to the activity of the parts. In those 
who take much exercise, the atoms which compose the 
body must be changed much oftener than in the indolent 
and sedentary. In the same manner, the exercise of par¬ 
ticular limbs will cause them to appropriate a much largei 
amount of nutritive matter. An individual who walks 
much, will therefore develop more fully the muscles of the 
lower limbs; while the blacksmith will develop more 
fully the muscles of the arms. But a palsied limb, which 
has fallen into disuse, will emaciate and grow smaller. 

225. Physiologists have never been able to determine 
with certainty by what means each tissue selects from the 
blood just those elements which form its own composition. 
We must therefore regard it as one of those ultimate facts 
in nature, which lie beyond the limits of our present 
knowledge. 

226. It is supposed, however, “that the process of nutri¬ 
tion consists in the growth of individual cells composing 
the fabric, and that these derive their support from the 
organic compounds with which they are supplied by the 
blood, and that the structure composing every separate 
portion of the body has what may be termed a special 
affinity for some particular constituents of the blood, caus¬ 
ing it to absorb from that fluid, and convert into its own 
substance, certain of its elements.” 

227. When the amount of alimentary materials con¬ 
verted into tissue exceeds the waste of the decaying ele- 

How is this illustrated by a movement of the arm ? The rapidity of the 
changes are in proportion to what? What is the effect of exercising particu¬ 
lar limbs? Have physiologists been able to determine the means by which 
each tissue selects those elements which form its own composition? In what 
is the process of nutrition supposed to consist? When is the body said tc 
increase in size? 


SECRETION. 


101 


ments, the body is said to grow old, or increase in size, 
When the nutrition is less than the loss by decomposition, 
the body becomes emaciated. In the earlier periods of life, 
nutrition goes on rapidly, speedily producing the renewal 
and growth of the various parts of the body. When the 
body has attained its full size, the process of nutrition be¬ 
comes less active as life advances. In middle life, nutrition 
just equals the loss by decomposition; in old age, the body 
becomes so imperfectly nourished, that it is literally worn 
out with years. 


CHAPTER IX. 

SECRETION. 

228. Secretion is the process in plants and animals by 
which various materials are separated from the circulating 
fluid. From the sap of different plants, in which chemical 
analysis cannot detect the slightest difference, the most 
opposite and varying products are elaborated. Thus, the 
sap of the poppy produces the narcotic opium; that of the 
cherry-laurel, the deadly prussic acid; that of the olive, its 
; oil. Acids are obtained from some; alkalies, from others; 
sweet juices, nutritive principles, oils, and resins, from 
others; different secretions are obtained from different 
« parts of the same plant. In animals, the nutritious milk 
is secreted in one organ; bile in another; mucus, saliva, 
urine, &c. ; in others; and yet we are wholly ignorant cf 
the reasons why, by the same process and out of the same 
; fluid, so many different secretions are formed. All that 
we know is in regard to the structure of the organs con- 
I cerned in elaborating those various secretions. 

When is it said to become emaciated ? How does the activity of nutrition 
vary at different periods of life? What is secretion? What is said of the 
secretions obtained from the sap of plants? What are some of the secretions 
obtained from the sap of plants ? What are some of the secretions obtained 
lfom animals? 

8 








102 


CLASS-BOOK OF PHYSIOLOGY. 


229. The process of secretion, both in the animal and 
in the plant, is performed by cells, which are arranged in 
different methods, according to the structure of the organ 
in which they are found. Those cells seem to have the 
power of separating the peculiar secretion of each organ 
from the blood of the membrane with which they are con¬ 
nected. At parts where it is necessary that the secretion 
should be particularly abundant, the secreting surface is 
increased by great numbers of little bags or follicles lined 
with cells. 

"^230. There are two kinds of materials which are secreted 
from the blood of man, namely, those which go form 
such products as may serve some useful purpose in the 
animal economy, called secretions , and those which would 
be injurious, if retained in the system, called excretions . 

231. The two principal divisions of the secreting ap¬ 
paratus are membranes and glands. The principal secret¬ 
ing membranes are the serous and mucous membranes 
and the skin. 

232. The serous membrane forms closed sacs, which 
envelop all the organs of the body not exposed to the air, 
and also line the cavities in which those organs are con¬ 
tained. The brain, heart, lungs, and the organs inclosed 
in the abdomen, are all protected by this membrane. A 
gaseous fluid is constantly secreted by it, which makes its 
surface smooth and moist, so as to render the movements 
of the organs free and easy, and prevent any friction where 
the surfaces come in contact with each other. 

233. A peculiar variety of the same membrane is found 
at the ends of the bones, which secretes a thick fluid to 
lubricate the joints, called synovial fluid, from its resem¬ 
blance to the white of an egg. 

How is the process of secretion performed in animals and in plants ? What 
power do the cells seem to possess"? How is the secreting surface increased 
in particular parts ? What two kinds of materials are secreted from the blood 
of man? What are the principal divisions of the secreting apparatus? What 
organs are protected by the serous membrane ? What is secreted by the serous 
membrane ? How are the ends of the bones protected ? 


SECRETION. 


103 


234. The mucous membrane lines all those passages 
which communicate with the air—as the nose, the larynx, 
the bronchi and their minute ramifications in the lungs, and 
the whole digestive apparatus—from the mouth through 
the intestines. It secretes a peculiar viscid fluid, called 
mucus, which serves to moisten and defend this membrane, 
and aid in the exercise of smell and taste. When the 
mucous membrane becomes irritated or inflamed, as in 
common colds, causing catarrh, or in diarrhea and dysen¬ 
tery, it secretes a large amount of mucus, which some¬ 
times becomes quite thick and hard, like the white of an 
egg when boiled or hardened by alcohol. 

235. The most important of the secreting glands are the 
liver , the kidneys, the salivary and' lachrymal glands. 

236. The liver is found in some form in nearly all ani¬ 
mals which possess a digestive cavity. In man and the 
mammalia, it is made up of a vast number of minute lob¬ 
ules, of irregular form. Each lobule contains a mass of 
cells, and a plexus of biliary ducts, with three blood-ves¬ 
sels; namely, the hepatic artery, the portal vein, and the 
hepatic vein. {Figs. 5 and 6, Pl. YIII.) 

237. The hepatic artery furnishes nourishment to the 
substance of each lobule; the portal vein provides blood for 
the secreting operation; and the hepatic vein carries back 
the blood derived from both sources. The bile is taken 
up from each lobule by the plexus of biliary ducts which 
finally unite into a common duct. 

238. The function of the liver in secreting bile is ol 
very great importance to health. When the liver becomes 
inactive, or ceases to perform its office perfectly from any 

What passages are lined by the mucous membrane? What is the secretion 
of the mucous membrane called? What is its use? What are the most 
important of the secreting glands ? In what animals is the liver found ? Of 
what is the liver made up in man and the mammalia ? What does each 
lobule contain ? Describe the use of tbe hepatic artery—the portal vein—the 
hepatic vein. How is the bile taken up from each lobule ? What is said 
of the function of the liver? How is the health affected by inaction of 
the liver ? 



104 


CLASS-BOOK OF PHYSIOLOGY. 


other cause, the health very soon becomes impaired, caus¬ 
ing head-ache, languor, and nausea, if not more serious 
disease. The object of the secretion of bile is to separate 
from the blood those materials which would be injurious 
if retained in the system, though in the form of bile they 
afford important aid to the process of digestion. 

239. The kidneys also secrete or separate from the blood 
certain superfluous or waste materials. 



Fig - 40.—Section of Kidney.—a, 
external or vascular portion; b , b, 
medullary portion ; c, pelvis; d , 
ureter. 



Fig . 41.—Structure of tiie Parotid Gland. 


240. The external or cortical substance of each kidney is 
composed of an infinite number of ramifications of blood¬ 
vessels. The central or medullary part is formed of nu¬ 
merous straight tubes, which are collected into conical 
bundles, all terminating in one common basin or pelvis, as 
it is called. {Fig. 40.) As the urine is secreted in the 
pelvis of the kidney it is conveyed by the tubes, named 
ureters, into the bladder. 

241. The salivary glands, including the parotid, sub¬ 
maxillary, and lingual, and the lachrymal glands, are all 


What is the object of the secretion of bile ? What is the function of the 
kidney 1 Of what is the cortical substance of the kidney composed 1 Of 
what the central or medullary portion 1 What do the salivary glands include ? 








SECRETION. 


105 


similar in structure. They are composed of an aggrega¬ 
tion of small lobules, the cells of which open by minute 
ducts, which converge and unite into larger and larger 
ducts, and at last into a common trunk, through which 
their contents are carried to the point where the peculiar 
fluid of each is needed. The structure of the parotid 
gland is represented in jig. 41. 

242. The quantity and character of the secretion are 
influenced by variations in the quantity of blood, and of 
the peculiar materials for any secretion which it contains, 
and by the condition of the nervous system. An increase 
in the quantity of blood which passes through a gland, 
generally increases its secretions. Through the nerves, 
various emotions of the mind influence the secretions: the 
thoughts of food increase the flow of saliva, and grief or 
pain produces a flow of tears. In the case of milk, not 

* only the quantity, but the quality, of the secretion is influ 
enced by the state of the mind. 

243. The office of excretion is especially performed by 
the lungs, the liver, the kidneys, and the skin. The lungs 
throw off carbon and hydrogen, in the form of carbonic acid 
and vapor. The liver separates the same elements from 
the blood, in the form of a peculiar fatty matter; the kid' 
neys, in the form of urine; and the skin, in that of sweat. 
If the excretions, or either of them, be checked, they 
speedily accumulate in the blood, and often lead to the 
most deleterious results. 

Of what are the salivary and lachrymal glands composed ? What circum¬ 
stances influence the quantity and character of the secretions? How do 
emotions of the mind influence the secretions? By what organs is the func¬ 
tion of secretion performed? What substances are thrown off from the 
lungs ?—the liver ?—the kidneys ?—the skin ? 




106 


CLASS-BOOK OF PHYSIOLOGY. 


CHAPTER X. 

THE SKIN. 

244. The skin is the external covering of the body, and 
consists of two principal layers. The epidermis, or scarf- 
skin, and the dermis , or true skin. 

245. The epidermis is made up of cells in different 
stages of drying. Those nearest to the true skin are 
rounded or oval in form, and, as they approach the surface, 
lose by evaporation the fluid they contain, and are gradu¬ 
ally converted into scales or scarf-skin. The outer layers 
of the epidermis are constantly being worn off, and new 
layers as constantly formed from within. Thus, each layer 
is gradually pushed from within, outward. 

246. The epidermis is raised from the true skin in the 
formation of a blister, and portions of a considerable extent 
peal off after some diseases, such as scarlet fever. It is also 
removed with the hair, in the process of dressing the hides 
of animals, leaving the true skin with a smooth surface. 
The minute scales of which the surface of the scarf-skin 
is composed, are constantly cast off by ablution and fric¬ 
tion of the skin. On the scalp, these scales are removed 
in the form of “dandruff” or scarf. 

247. The pigment cells, containing the coloring matter 
which causes the different varieties of complexion, are de¬ 
posited in the soft layers of the cuticle next to the true 
skin. {Fig. 8, Pl. IX.) In Albinoes there is no coloring 
matter: the skin presents a uniform and pearly whiteness, 
and the hair is also white and colorless. 

248. The epidermis is not provided with either nerves 

What are the principal layers of the skin 1 How is the epidermis formed ? 
What becomes of the external layers of the epidermis ? How is the epider¬ 
mis raised from the true skin ? How are the minute scales of which the 
surface of epidermis is composed, cast off? How are the different varieties 
of complexion caused 1 Where are the pigment cells deposited 1 Why ia 
the epidermis a hard, insensible membrane 1 


































































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PLATE I 


THE SKIN. 


Figure 1.- A Portion of the Epidermis of the Palm of the Hand, magnified by a rimple 

lens , Showing the direction of the rugae or wrinkles, and the arrangement of the apertures 
cf the sudoriferous glands. 

Figure 2. - A portion of the same, magnified one hundred diameters. 

Figure 3. - A J>ansverse Section of the Ridges of the Epidermis of the Palm cf the 

Hand, Showing a side view of the apertures of the sudoriferous glands, their spiral ducts, 
the thickness of the epidermis in that situation, its composition of layers of cells, and its 
mode of connection with the true skin. 

Figure 4. - A Portion of the Epidermis from the back of the Hand, Showing the dis¬ 

position of the folds in that situation, the arrangement of the papillae, the disposition of 
the hairs, and the apertures of the sudoriferous and sebaceous glands, magnified with a 
simple lens. 

Figure 5.- A piece of the same, magnified one hundred diameters, Showing that each 

line is a furrow or groove, a provision which allows of very great extension of the epidermis. 

Figure 6.- A Square of Cuticle, seen upon its internal surface. — a, The sulci, or 

depressions, which correspond with the ridges of the external surface, b, The ridges 
which correspond with the furrows of the external surface. 

Figure 7.- The Under Surface of the Epidermis, Showing the pigment-cells, which 

contain the coloring matter of the skin.—These cells are seen to be collected principally 
in the furrows between the papillte. 

Fioure 8. - The Pigment Cells of the Negro , Showing that his darker complexion i* 

owing to the darkness of the color of the pigment contained in these cells. 






Hartford. Conn 





























































































THE SKIN. 


Ill 


or blood-vessels, and is therefore a bard, insensible mem¬ 
brane, investing the true skin, and protecting it from im 
mediate contact with external objects. Where the friction 
or pressure to which it is exposed is very great, it becomes 
quite thick and horn-like. Thus, on the palms of the 
hands and the soles of the feet, it is much thicker than 
any where else. 

K 249. The epidermis is marked on the surface by a net¬ 
work of lines, which are more numerous and larger near 
the joints, where they form deep wrinkles. It is perforated 
by numerous openings or pores, for the passage of hairs 
and for the perspiratory ducts. (Figs. 1, 2, 3, Pl. IX.) 

250. The dermis or true skin is a firm, elastic membrane, 
composed of innumerable fibres, interwoven in every di¬ 
rection by a vast number of blood-vessels, lymphatics, 
and nerves. 

251. Within and beneath the true skin lie the perspira¬ 
tory glands, the hair follicles, and the sebaceous or oil 
glands. Its outer surface is studded with an infinite num¬ 
ber of minute conical elevations, called papillce. (Fig. 5, 
Pl. X.) 

252. Each papilla is composed of a minute blood-vessel 
and a nerve, both of which form a loop, or are bent several 
times upon each other. The blood-vessel is usually the 
capillary termination of a vein in an artery. These pa¬ 
pillae are the seat of the sense of touch, and are so numer¬ 
ous over all the external parts of the body that the skin 
cannot be punctured by the finest needle without wounding 
some one of them. They are the most numerous in those 
parts of the body most exposed to the action of foreign 
agents, or where the sense of touch is most acute. They 
are most prominent and most densely set on the ends of 

How is the epidermis affected by pressure ? How is it marked on the 
surface ? By what is the epidermis perforated ? Describe the dermis or true 
skin. What lies beneath the true skin ? Of what is each papilla composed 1 ? 
What is the blood-vessel? What sense is located in the papillae ? Where are 
they the most densely set ? 





112 


CLASS-BOOK OF PHYSIOLOGY. 


the fingers and in the palms of the hands, where each 
raised line is composed of a double row of them. 

253. The perspiratory glands are imbedded in the fatty ; 
layer beneath the skin, through which the ducts pass with 
a beautiful spiral coil, as represented in fig. 3, Pl. IX., and , 
Jig. 1, Pl. X., and open at the surface obliquely, so as to 
form a kind of valvular opening. These glands are very i 
numerous over all parts of the body, being on an average 
about 2800 to every square inch of surface, or about 
7,000,000 in all. 

254. Fluid is constantly exhaled from the perspiratory 
glands, and carried off by evaporation as fast as it reaches 
the surface, in the form of insensible perspiration. During 
active exercise, or exposure to heat, it is poured off more 
rapidly, accumulating on the surface in drops, and is then 
called sensible perspiration. In warm, dry weather, when 
evaporation takes place rapidly, the amount of insensible 
perspiration may be very great. It has been estimated 
that from two to three pounds are daily exhaled from the 
skin of an adult, though the amount of insensible perspira¬ 
tion may be very materially increased or diminished ac¬ 
cording to the quantity of fluid taken into the system. 

255. This watery exhalation serves a very important 
purpose in the animal economy in maintaining a uniform 
standard of heat, and in carrying off substances that 
would be highly injurious if retained in the system. The 
most abundant matters thus carried off are carbonic acid 
and water. 

256. The sebaceous or oil glands are also imbedded in 
the fatty layer beneath the skin: their ducts open either 

Where are the perspiratory glands located? How do the perspiratory 
ducts pass through the skin ? How numerous are the perspiratory ducts 
What is constantly exhaled from the perspiratory ducts? What is sensible 
and what insensible perspiration ? How much is estimated to be exhaleci 
from the skin of an adult daily ? How may the perspiration be increased or 
diminished ? Of what use in the animal economy is this watery exhalation 1 
What matters are carried off? Where are the oil glands located ? Where 
do their ducts open? 



THE SKIN. 


118 


on the surface of the skin or directly into the follicles of 
the hair. They are most numerous in those parts largely 
supplied with hair, as the scalp and face, and are thickly 
distributed in the nose, lips, and ears. The oily secretion 
of these glands serves to keep the skin supple and soft, 
and prevents it from drying and cracking. 

257. Along the margin of the eyelids there is a row of 
these glands, which keep the lids smooth, and prevent the 
tears from trickling over their edges. Occasionally one of 
these glands becomes inflamed, and forms what is called a 
sty. In the passage of the ears, another set of these 
glands secretes the ear-wax. 

258. The hair and nails are both regarded as appendages 
to the skin, and contribute to its defence. Each hair 
originates in a small follicle or body in the fatty-substance 
just beneath the skin. {Fig. 2, Pl. X.) Sebaceous glands 
open into these follicles, and furnish the oily material with 
which the hair is anointed and softened. The coloring 
matter of the hair is secreted by cells within the follicles, 
and through a deficiency of this secretion the hair becomes 
gray, and finally white. The shape of individual hairs is 
cylindrical for the smaller kinds, and oval for those which 
grow to any length. When left to their natural growth, 
the end or tip of the hair is always conical or pointed; 
and in most animals the portion of the hair next to the 
skin is smaller than the more distant portion. After the 
growth of the hair has reached a certain point, its nutrition 
ceases, and the hair falls off, to be replaced by another. 
In most animals, this occurs periodically, and is called 
moulting , or shedding of the coat. In the same manner 

In what parts are the oil glands most numerous ? Of what use is the oily 
secretion ? What purpose do these glands serve on the margin of the eyelids 1 
Wfiat are these glands called when they become inflamed 1 ? What are 
regarded as appendages of the skin ? How does each hair originate ? How 
are the hairs softened ? How is the coloring matter secreted ? What causes 
the hair to become gray 1 What is the form of each hair 1 What is the 
form of the end of hair 1 What part of the hair is the smallest in mos: 
animals ? How do most animals shed their hair 1 



LJL4 


CLASS-BOOK OF PHYSIOLOGY. 


the antlers of deer are produced very rapidly till they have 
attained their growth, when they begin to harden at the 
base, gradually obstructing the vessels which nourish them, 
and then fall off, to be again replaced by a new and more j 
beautiful production. 

259. The nails are produced from the true skin by an 
organization of cells similar to the epidermis. Each nail 
is inserted between a fold of the skin, which is reflected 
backward to the root of the nail, and then passed forward 
beneath its under surface, to which it adheres. {Fig. 3, 
Pl. X.) In the process of growth, additions are made to 
its under* surface and to the free edge of its root at the 
same time, so that growth in thickness and growth in 
length proceed together. 

260. The use of the nails is to support and protect the 
ends of the fingers in grasping, and they are particularly 
useful in taking hold of minute objects. 

261. The structure of the scales, feathers, hoofs, and 
horns of different animals, like that of the nails and hair, 
is similar to the epidermis, to which they belong. The 
feathers of birds are remarkable for the wonderful manner 
in which they combine strength and lightness with surpass¬ 
ing beauty. The stem or body is formed by an apparatus 
which may be likened to a hair follicle; but there are 
some additional parts, for the production of the laminae 
that form the vane of the feather, which are joined to the 
stem during its production. These laminae, when perfectly 
formed, are connected by minute barbs at their edges, 
which hook into one another, and thus give to the entire 
vane a very strong resisting surface. The substance of 
which feathers consist is a very bad conductor of heat; 
and when they are lying one upon the other, they form 
an admirable protection against cold and moisture. 

In what manner do deer shed their antlers ? How are the nails produced ? 
Describe the insertion of the nail and the process of its growth ? What is the 
use of the nail 1 What do the feathers, hoofs, and horns of animals resemble 
in their structure 1 For what are the feathers of birds remarkable ? How 
are they formed 1 























































* 




















PLATE X 


THE SKIN. 


Figure 1. - A Section of all the Layers of the Skin. — a, The epidermis, b , c, The two 

layers of the cutis vcra, d, A sweat-gland, surrounded by cells of fat, and sending its 
spiral duct upward through all the layers of the skin to the surface. 

Figure 2.- A Section of the Skin , Showing the hair follicles and sebaceous glands. 

a, a, Sebaceous glands, opening into the hair follicle, b , A hair, with its follicle, c, sur¬ 
rounded by fat-cells. 

Figure 3.- A Section of the Thumb , Showing the manner in which the nail is inserted 

between the folds of the skin.— a, The last bone of the thumb, b , The cuticle reflected 
upon the root of the nail, c, The nail, d, The cuticle of the point of the thumb, contin¬ 
uous with that at the inner surface of the nail. 

Figure 4.- Papilla of the Skin, magnified, containing expansions of the nerves and 

of the capillary blood-vessels. 

Figure 5.- The Spiral Arrangement of the Papilla at the ends of the Fingers^ iti 

which the sense of touch is especially seated. , 

Figure 6. -Sensitive hairs supplied with nerves. 


\ 






PL. X 


Fi§.1. 



: Xello|g,Li£h.. 





Hartford, Conn. 


T 




























































































- 














* 




’ 



THE NERVOUS SYSTEM. 


119 


CHAPTER XI. 

THE NERVOUS SYSTEM. 

* 262. The nervous system of man and the higher animals 
consists of the brain, the spinal cord, the ganglia, and the 
nerves. 

263. The brain is the centre of sensation. The spinal 
cord, the ganglia, and the nerves are conductors of nervous 
impressions. 

264. The office of the nerves is to convey impressions 
made upon their extremities to the brain, the organ by 
which the mind becomes conscious of external objects, and 
to convey impressions from the brain to the ultimate dis¬ 
tributions of the nerves. 

265. The nerves are divided into two classes—nerves of 
sensation and nerves of motion. Thus, if the hand be acci¬ 
dentally placed in contact with a hot iron, the feeling of pain 
is communicated to the brain by the nerves of sensation, 
and the impulse to remove the hand is immediately return¬ 
ed from the brain by the nerves‘of motion. Nerves of sen¬ 
sation and nerves of motion have a separate origin from the 
nervous centre, though they are apparently the same in 
structure, and are usually in the same bundle of nerve fibres. 

266. Nerves have no power of originating impressions. 
Those of sensation are stimulated by external agents, and 
those of motion by the will or some other force generated 
in the nervous centres. 

267. Nervous force moves along a nerve, like the elec¬ 
tric fluid along a wire, without the lapse of an appreciable 
period of time in its passage. Each nerve-fibre can carry 
only one kind of an impression: a nerve of motion can 

Of what does the nervous system consist ? Of what is the brain the centre ? 
What is the office of the nerves ? How are the nerves divided? What illus¬ 
tration can you give of the function of both ? Have the two classes of nerves 
the same origin from the nervous centre? Do nerves originate impressions? 
How is each class of nerves stimulated ? How does nervous force move along 
a nerve? Can a single nerve-fibre convey more than one kind of impression? 
What does a nerve of motion convey ? What a sensitive fibre ? 


120 


CLASS-BOOK OF PHYSIOLOGY. 


convey only motor impulses; a sensitive fibre can transmit 
only such as may produce sensation, as that of light or 
sound. 

268. The fibres of motor nerves, which are distributed 
to the muscles, spread forth from their trunks into branches, 
which anastomose with each other, forming a kind of net¬ 
work through the muscle; but the nerves of sensation, 
which start from the skin, and convey impressions to the 
brain, originate in minute elevations or papillae on the 
surface of the true skin, and in their infinite ramifications 
is seated the sense of touch. 

269. In order that an individual may become conscious 
of what is passing around him, an impression must be 
made by external objects upon the organs of the sensitory 
nerves in the papillae, and this impression must be con¬ 
ducted by the nervous trunk to the brain, and then it 
becomes a sensation. On the other hand, before the mind 
can cause any movement of the body to be here formed, 
an emotion or act of the will must produce a change at 
the origin of the motor nerves in the brain, and this 
change must be conducted along those nerves to the mus¬ 
cles, where it excites a contraction or muscular effort 
suited to the required purpose. 

270. There is another kind of movement which does 
not seem to be excited by impressions made on the brain. 
They are called reflex movements , because impressions of 
this class are conducted only to certain nervous centres, 
and are then reflected back to the organ whence they 
originated. 

271. Movements of this class are more particularly oon- 

How are the motor fibres distributed to the muscles ? How do the nerves 
of sensation originate ? What sense is seated in the ramifications of the 
nerves of sensation 1 How does an individual become conscious of what is 
passing around him 1 What takes place before any movement of the body can 
be effected 1 What are those movements called which do not seem to be 
excited by impressions made on the brain 1 Why are uiey called reflex move¬ 
ments ? In what changes are the reflex movements particularly concerned ? 




THE NERVOUS SYSTEM. 


121 


cerned in those changes which have for their object the 
maintenance of organic life, such as the movements of the 
digestive canal, the respiratory movements, or the contrac¬ 
tion of the eyelids and pupil, to exclude a portion of the 
rays of light when they are too intense for the retina. 

272. The nervous centres of reflex action are the ganglia 
and the spinal cord. The exercise of this power by the 
ganglia and spinal cord is a remarkable arrangement, by 
which those processes that are in constant action for the 
maintenance of life are performed without any exercise 
of the will or any consciousness of the mind. It is to be 
feared that, if the brain was made sensitive to all the 
digestive and respiratory movements, the mind of many 
individuals would be constantly occupied with vigilant 
inspection of these hidden processes of nature. 

273. The true nature of reflex action can be more easily 
comprehended by studying the comparative development 
of the nervous system in different groups of animals, and 
by noting the powers of its simplest, compared with its 
most perfect developments. 

274. One of the simplest forms of the 
nervous system is found in the ascidia, 

{fig. 42,) one of the lowest, of the class of 
mollusca. In this and similar animals, 
we find only a single ganglion or nervous 
centre. At a is seen the orifice by which 
water enters for supplying the stomach 
with food, and at b that through which 
it passes out again. Between these ori¬ 
fices is the single ganglion, c , which sends 
filaments to both orifices, and also over Fig 42 ._ NKRVOts Syb 
the surface of the envelop or mantle, d. ° TEM 0F Ascidia - 



What are the centres of reflex action ? What particular advantage may 
be supposed to result from this arrangement ? How may the true nature of 
reflex action be more easily comprehended 1 In what animal is one of the 
simplest forms of the nervous system found 1 Describe the nervous system of 
the ascidia and the phenomena of life exhibited by that animal. 


122 


CLASS-BOOK OF PHYSIOLOGY. 


These animals are mostly fixed to one spot during their 
whole existence. The continual entrance and exit of the 
currents of water constitute the only phenomena of life 
which they exhibit, except when the current draws in an 
injurious substance. The mantle then contracts, causing 
a jet of water to issue from each orifice, and throw off the 
offending material. This little animal has no eyes or other 
organ of special sense. The small tentacula or feelers, at 
the upper orifice, are the only parts which seem to be 
peculiarly sensitive; and the irritation caused by the con¬ 
tact of a hard substance with these, or with the general 
surface of the body, produces an instinctive contraction of 
the mantle, for the purpose of getting rid of the irritating 
cause. This contraction can only be performed by the 
aid of a nervous system, which has the power of receiving 
impressions, and of exciting the most distant parts of the 
body to act in accordance with them. 

275. Those animals which in¬ 
habit bivalve shells exhibit the 
powers of respiration, sensation, 
and voluntary motion, and pos¬ 
sess a corresponding develop¬ 
ment of the nervous system. In 
the nervous system of the pecten 
or scallop-shell, {fig . 43,) there is 
a large ganglion at B, which dis¬ 
tributes branches to the gills and 
mouth, and regulates the re¬ 
spiratory movements. Another 
ganglion, c, is connected with the 
thick fleshy part on which the 
animal crawls, and which is called its foot. Near the sides 
of the oesophagus, e, are situated two other ganglia, A, a, 
the nerves of which are distributed to the sensitive ten¬ 
tacula which guard the mouth. These two cephalic 

Describe the nervous system of the pecten. 



Fig . 43 .— Nervous System of Peg- 
ten. —A, A, ganglia of the head; B, 
respiratory ganglion; C, ganglion of 
the foot; e, oesophagus. 







THE NERVOUS SYSTEM. 


123 


ganglia, or ganglia of the head, evidently correspond to 
the brain of higher animals, being the instruments of sen¬ 
sation and voluntary power, and they exert a controlling 
direction over the movements of the animal; while the 
pedal and bronchial ganglia (those of the foot and of 
respiration) minister to the reflex actions of the organs 
supplied by them. 

276. In animals of higher orders, the ganglia are more 
numerous as the variety of functions to be performed 
becomes greater; and in proportion as we ascend the scale, 
the cephalic ganglia become more and more developed, 
and more and more elevated above the oesophagus, until 
they finally meet on the central line above it, and, in the 
more perfect animals, take their place in the top of the 
head—overlooking, as it were, all the other organs. 

277. The nervous system of in¬ 
sects whose actions are generally 
energetic and rapid, and in which 
the apparatus of motion (wings and 
legs) is highly developed, presents 
a marked difference from that of 
the Mollusca, which are usually 
inert and sluggish. It consists of a 
large ganglion in the head, analo¬ 
gous to the brain of vertebrated 
animals, and a chain of ganglia, one 
for each segment of the body, uni- Fitr 44 
ted by a double cord, as in fig. 44. 

In the larva or caterpillar, before it is changed into the per¬ 
fect insect, the nerves arising from the ganglia are chiefly 
distributed-to the muscles of the legs, and the ganglia are 
only repetitions of each other, being nearly of uniform size; 
but in the perfect insect, the wings and legs, which con- 



Nervous System of ah 
Insect. 


What is said of the ganglia in the higher orders of animals 1 How does 
the nervous system of insects compare with that of the Mollusca ? Of what 
does the nervous system of insects consist ? How are the ganglia united ? 





124 


CLASS-BOOK OF PHYSIOLOGY. 


stitute the apparatus of locomotion, are confined to the 
thorax, and the segments of the abdomen have no legs. 
Accordingly, the ganglia of the thorax, in the perfect insect, 
are found to be very much increased in size, and sometimes 
concentrated in one mass, while those of the abdomen are 
much smaller. 


278. This difference is shown in 
fig. 45, where A represents the nerv¬ 
ous system of the caterpillar, from 
which is produced a species of sphinx 
or hawk-moth, and B that of the moth 
itself. In B, the cephalic ganglion is 
much larger than that of A, since it 
has become connected with more per¬ 
fect eyes and other organs of sense. 
The ganglia which supply the wings 
and legs (those next below that of the 
head) are also greatly enlarged and 
concentrated, while the abdominal 
ganglia are diminished, and some of 
them are wanting. The whole chain 
'is also considerably shortened, the 
body of the moth not being so long 
as that of the caterpillar. 

279. The chain of ganglia in in- 

Fig . 45— Nervous System of Sects is found to Consist of tWO dis- 

the caterpillar; B, that of the tinct tVCLClS - One IS Composed of 

perfect insect. 'nerve-fibres only, and passes from 

the cephalic ganglion over the surface of all the other gang 
lia, giving branches to the nerves which proceed from each 
other, while the other tract connects the ganglia themselves. 
Thus, each segment of the insect has a distinct nervous 
connection with its own ganglion, and a sympathetic con¬ 
nection with the others, extending to the cephalic ganglion, 



How do the ganglia of the perfect insect differ from that of the larva or 
caterpillar ? Describe Fig. 45, with the difference between A and B. Ex¬ 
plain the arrangement of the ganglia of insects. 













THE NEKVOUS SYSTEM. 


125 


which seems to have a controlling influence over, all the 
rest, and alone to possess the faculty of sensation. Hence, 
the motions produced by the ganglia of the trunk, when 
the head of the insect is removed, although they may seem 
to indicate sensation, are found to be only reflex in their 
nature—a certain irritation producing a certain movement 
without choice, and probably without consciousness, on 
the part of the animal. 

280. Thus, if the head of a centipede be cut off while 
it is in motion, the body will continue to move as before; 
or if the body be divided as many times as it has segments, 
each portion will still continue to move, but all conscious¬ 
ness seems to be lost: for as the decapitated body comes in 
contact with an obstacle equal to its own height, it remains 
fixed against it, the legs moving as before, but without 
change of direction or the ability of surmounting the ob 
stacle—being no longer subject to the will of the animal, 
but performing reflex movements by the influence of their 
own ganglia. 

281. In vertebrated animals, (those which possess a back¬ 
bone or spinal column) the ganglia are no longer scattered 
through the body, but are united into one continuous mass; 
and this mass, constituting the brain and spinal cord, is 
inclosed within the skull and vertebral column, in such a 
manner as to be protected from the'injuries to which it 
would otherwise be liable. The brain in the higher ver- 
tebrata consists of a principal mass, called the cerebrum , 
which occupies all the front and upper part of the skull, 
and is divided into two hemispheres or halves by a mem¬ 
branous partition, running from hack to front, and of a 
smaller mass, called the cerebellum , situated beneath the 
cerebrum, at the back part of the skull. At the base of 
the cerebrum there are two ganglia, the olfactory and 

How is it shown in the case «f the centipede that consciousness depends on 
the cephalic ganglia ? How are the ganglia arranged and protected in verte¬ 
bral animals 1 Of what parts does the brain of the higher vertebrata consist ? 
What ganglia at the base of the cerebrum ? 



126 


CLASS-BOOK OF PHYSIOLOGY. 



the optic, which belong to the nerves of smell and sight. 
All these parts in the human brain will be particularly 
described. 

A 282. In the brain of a fish, 

{fig. 46,) the parts just men¬ 
tioned are beginning to ac¬ 
quire considerable develop¬ 
ment. The cerebral hemis¬ 
pheres (c, A), the optic ganglia 
(o, y>), the cerebellum (c, e), 
are plainly to be distinguish¬ 
ed, and their relative sizes are 
in proportion to the intelli¬ 
gence of the animal. Thus, 
brain of the the ganglia which control the 

shark ; ol, olfactory ganglia; spinal cord. sense 0 f sight are Very large, 

since this sense is possessed in a very high degree by 
fishes; while the cerebral hemispheres, to which belong 
more especially the manifestations of will and thought, are 
correspondingly smaller. The cerebellum also, which, as 
we shall see, is connected with the powers of motion, is 
large, as we should expect to find it in animals possessed 
of the power of rapid movement, and is larger in the ac¬ 
tive and rapacious shark than in the less energetic cod. 

The spinal cord is large, and is divided 
at the top, so as to form an opening be¬ 
tween its two halves. In man, as we 
shall see, this opening becomes entirely 
closed. 

283. In birds, the brain has made a 
considerable advance towards what it 
finally becomes in man. The cerebral 
Fig. 47 . Brain of a Bird, hemispheres (a, fig. 47,) are greatly in¬ 
creased in size, and cover in the olfactory ganglia entirely 

What is said of the brain of a fish 1 Describe Fig. 46. What parts are 
large and what small in a fish 1 What is the comparative size of the cerebral 
hemispheres in birds ? 









THE NERVOUS SYSTEM. 


127 


and the optic ganglia (b) partly. The cerebellum (c) is 
also much more developed, as we should expect from the 
variety of movements performed by birds, but is as yet un¬ 
divided into lobes. The spinal cord (d) is still of consider¬ 
able size, and is much enlarged at the points from which 
originate the nerves of the wings and legs. As might be 
inferred from these advancements in the structure of the 
brain, the intelligence of birds is vastly superior to that 
of the animals previously considered, and they are the 
first in the ascending scale which are capable of education 
or training. Did the limits of this work permit, we might 
thus go on to trace the progressive development of the 
brain through individual species of birds and mammalia, 
and to show at each step a corresponding advance in intel¬ 
ligence as we approximate to man. 

284. In man, the cerebral developments are greatly 
increased, while the spinal cord is diminished in size. The 
surface of the brain is not smooth, but divided by furrows 
into a series of convolutions, by which the surface over 
which the blood comes in relation with the nervous mat¬ 
ter is greatly increased, thus adding to the activity of the 
organ. The two hemispheres are more closely connected 
with each other by fibres running across from each side. 
The cerebellum is divided into two hemispheres. 

NERVOUS SYSTEM OF MAN. 

285. The nervous system of man and of the higher 
animals consists of two portions—the cerebrospinal and the 
sympathetic or ganglionic. The cerebro-spinal system is 
composed of the brain and spinal cord, with the nerves 
which proceed from them to the skin and muscles. It has 

What is said of the cerebellum ?—1the spinal cord 1 How do birds compare 
m intelligence with the animals previously considered ? How are the cere¬ 
bral developments in man ?—how the spinal cord ? How is the surface of the 
brain in man 1 Of what does the nervous system of man or the higher ani¬ 
mals consist 1 Of what is the cerebro-spinal system composed 1 What has 
it been called ? 


128 


CLASS-BOOK OF PHYSIOLOGY. 


i 


been called the nervous system of animal life, because it 
is that by which sensations are received and voluntary 
motions executed, and with which the mind is more im- t 
mediately connected. The sympathetic system is connected 
with the nutritive processes alone, and from its influence 
over the organs of the thorax and abdomen, has been 
called the nervous system of organic life. It consists of a 
chain of ganglia, communicating with each othsr by nerv¬ 
ous cords, extending from the head along each side of the 
oack-bone. Nerves proceed from it to the organs of di¬ 
gestion and secretion, and to the heart and blood-vessels. j 

SPINAL COED. 

286. The spinal cord is a long irregular cylindrical col¬ 
umn of nerve substance, surrounded by a membranous 
envelop, and inclosed within a long canal, formed by the 
vertebrae (or pieces of the back-bone). It extends from the 
head to the first or second vertebra of the loins, and is 
composed of both white and gray nervous matter. The 
white matter constitutes its greater portion, and is situated 
externally, while the gray matter occupies its central part. 
The spinal cord consists of two symmetrical halves, united 
in the middle line by a set of converging fibres, called a 
commissure, but separated anteriorly and posteriorly by a 
vertical fissure—the posterior fissure being deeper, but not 
so wide and distinct as the anterior. Each lateral half is 
marked by two longitudinal furrows, which divide it into 
three columns or tracts, called anterior, lateral, and poste¬ 
rior. There is a considerable enlargement of the cord in 
the lower part of the neck, at the part from which arises 
the large nerves which supply the upper extremities; and 
a similar enlargement is also found in the loins, at the 
origin of nerves which go to the lower extremities. 

With what is the sympathetic system connected, and what has it been call¬ 
ed ? Of what does it consist 1 What is the spinal cord 1 How is the canal 
in which it is lodged formed ? What is the extent of the spinal cord?--and 
of what does it consist 1 How are the two halves united 1 How is each 
half divided ? What enlargements in the spinal cord 1 




THE NERVOUS SYSTEM. 


129 


287. The number of nerves given off by the spinal 
cord is thirty-one on each side: eight pairs in the region 
of the neck; twelve in that of the back, corresponding to 
the twelve pairs of ribs; five in the loins, and six in the 
pelvis. Each of these nerves arises by two distinct roots, 
one springing from the anterior column, 
and the other from the posterior column 
of the cord, as in fig. 48—a pair of roots 
on each side, corresponding to each verte¬ 
bra. These roots (the posterior ones hav¬ 
ing first formed a ganglion) soon unite in 
a single trunk, which thus combines the 
properties possessed by both. The poste- ^s.-por™* or THK 
rior set of roots consists exclusivelv of fu p i”f L - Coil ,?^ showin? 
those fibres which convev impressions to ~ a i ®P inal cord ; 

_ . ■ posterior root; e,gang- 

the spinal cord and brain, and thus form * ion ; d, anterior root 
1 . 7 trunk formed by both; 

the nerves of sensation; while the anterior /> branch, 
roots consist of fibres which convey nervous influence 
from the brain and spinal cord to the muscles, and form 
the nerves of motion. Thus, if the spinal cord of an 
animal be laid bare, and the posterior set of roots be 
touched, acute pain is obviously produced; while, if the 
anterior roots be irritated, violent motions of the muscles 
supplied by the injured nerves are occasioned. 

2 38. The spinal cord is both a conductor of nervous 
impressions and a nervous centre of reflex action. When 
an impression is made on the extremity of a spinal nerve, 
it is transmitted to the spinal cord, and thence conducted 
to the brain, where alone it can be perceived by the mind. 
In like manner, the stimulus of the will which originates 
in the brain is conducted along the cord, and thence to the 

How many nerves are given off by the spinal cord? How many pairs arc 
given off in the neck—back—loins—pelvis? How does each nerve arise from 
the spinal cord? Of what fibres do the posterior roots consist?—the ante¬ 
rior ? What would be the effect of irritating the anterior or the posterior, 
if the spinal cord of an animal was laid bare? What two functions does the 
spinal cord perform ? Explain how it acts as a conductor of nerrous im¬ 
pressions. 





130 


CLASS-BOOK OF PHYSIOLOGY. 


nerves. In case the spinal cord is lacerated or torn 
asunder at any point, as sometimes happens in fracture 
of the spine, this communication to and fro between the 
brain and the nerves is interrupted, so that the will has 
no longer any control over the parts below the injury, nor 
is the mind conscious of any injury that may be inflicted 
on them. Thus, if the cord be severed in the loins, sensa¬ 
tion and the power of voluntary motion in the lower 
extremities will be lost, while they will be in full exercise 
in the upper extremities. 

289. The spinal cord is also a nervous centre of reflex 
action. During sleep, when the brain is inactive, respira¬ 
tion and all those movements necessary to life go on as 
usual: liquid poured into the mouth is swallowed—the 
body changes its position. An animal whose cerebrum 
has been removed, does the same things. A pigeon, for 
instance, has been kept alive for several months in that 
condition; running when pushed, flying when thrown 
into the air, drinking when its beak was plunged into 
water, and swallowing food when placed in its mouth, but 
at all other times appearing in a profound sleep. 

290. From such facts, it is evident that the spinal cord 
must possess a great degree of independent power; but 
it differs from that of the brain in this, that it is exerted 
without the concurrence of the judgment and the will; 
and the movements produced by it are rather like those 
of an automaton, set in motion by pulling certain wires or 
touching certain springs. Thus, the motions of a decapi¬ 
tated animal are never spontaneous, but always excited 
by a stimulus of some kind. 

What are the effects of lacerating or dividing the cord ? Explain how tne 
spinal cord is a nervous centre of reflex actions? Does the spinal cord pos¬ 
sess any degree of independent power? How does it differ from that of the 
brain ? 




THE NERVOUS SYSTEM. 


131 


MEDULLA OBLONGATA. 

291. At its upper part the spinal cord becomes greatly 
enlarged, and forms a bulb-shaped body, called the medulla 
oblongata, which is inclosed within the skull, and through 
which the connection between the spinal cord and the 
brain is preserved. Its columns are continuous with those 
of the spinal fiord, but are more prominent, and it contains 
a larger quantity of gray matter. It is connected with the 
nerves of respiration, mastication, and deglutition, and 
may be considered as the common centre of the cerebro¬ 
spinal system. 

292. The medulla oblongata differs from the rest of the 
spinal cord in its functions mainly in the importance and 
extent of the actions governed by it. Like the cord, it is 
a conductor of nervous impressions; but it has a wider 
extent of function, since all impressions which pass to and 
from the brain and spinal cord must be transmitted through 
it. Motor impressions are transmitted through its anterior 
columns, and sensitive impressions through its posterior 
columns. Thus, if one of its anterior columns be divided, 
the animal will lose the power of motion in one half of 
the body, while its sensation will remain unimpaired. 

293. The functions of the medulla oblongata, as a nerv¬ 
ous centre, are more immediately important to the main¬ 
tenance of life than that of any other part of the system. 
The nervous force necessary for deglutition and respira¬ 
tion is generated in this organ. It has been proved by 
repeated experiments that the entire brain may be cut 
away, in successive portions, and life yet continue for a 
considerable period, and the respiratory movements be 

Where is the medulla oblongata? How is it formed? What is said of its 
columns? With what functions are its nerves connected? How does the 
meduHa oblongata differ from the rest of the spinal cord? Of what import¬ 
ance to the maintenance of life are the functions of the medulla oblongata? 
By what experiments has it been proved that life can be maintained so long 
as this portion remains uninjured? 


132 


CLASS-BOOK OF PHYSIOLOGY. 


uninterrupted. Life may also continue wlien the spinal cord 
is in like manner cut away from below upward as high 
as the phrenic nerve, which commences near the throat. 
In some of the amphibia, (tortoises, frogs, &c.,) the brain 
and spinal cord have both been thus removed, and still 
respiration and life continued so long as the medulla 
oblongata was untouched. But a very slight wound at its 
central portion will produce suffocation and sudden death. 

294. The power of reflex action is more apparent in this 
than in any other portion of the nervous centres. By this 
power, the respiratory movements are carried on. Thus, 
the application of stimuli to many parts of the body, the 
nerves of which transmit impressions to the medulla, will 
cause respiratory movements by reflection through the 
nerves which proceed from the medulla to the muscles 
concerned in respiration. This accounts for the u catching 
for breath ” produced by dashing cold water in the face. 
Convulsive movements are also produced through the 
agency of this part of the cord. In those convulsions 
which result from the teething of children, in lock-jaw, 
and other like diseases, death usually ensues from suffoca¬ 
tion—the muscles of respiration becoming so fixed that the 
air cannot be breathed. 

THE BRAIN. 

295. The human brain consists of two principal portions 
•—the cerebrum or large brain, and the cerebellum or small 
brain—protected by their membranes, and inclosed within 
the cranium or skull. The cerebrum, which constitutes 
nearly seven-eighths of the whole mass, occupies all the 
upper and anterior portions of the cranium, and is divided 

What has been said of the power of reflex action in this portion? What 
effects are produced on the respiratory movements by stimuli applied to other 
portions of the body? How are convulsions often produced ? What is usually 
the immediate cause of death in such cases? Of how many portions does the 
brain consist, stnd what are they called^ What portion of the cranium i a 
occupied by the cerebrum? 





THE NERVOUS SYSTEM. 183 

into two hemispheres or lateral halves. These are con¬ 
nected by transverse bands or commissures of nervous 
matter, and each hemisphere has three prominent masses 
or lobes—one at the forehead, one at the temples, and one 
at the back of the head. Its surface is intersected by deep 
fissures and eminences, which produce those winding ine 
qualities called convolutions. 

296. The nervous tissue of the cerebrum is composed 
of white and gray substances, disposed in a peculiar man¬ 
ner: a layer of the gray substance occupies the surface, 
and follows all the irregularities of the convolutions, while 
the white substance is placed in the central parts. Thus, 
each convolution consists of a layer of gray substance at 
the outside and of white substance within. The manner 
in which the two substances are thus arranged to form the 
convolutions, may be rudely illustrated by taking two 
pieces of cloth, laying one upon the other, and collecting 
them up into folds in a globular shape. By such arrange¬ 
ment, the surface over which the blood comes in contact 
with the nervous matter is greatly increased, and it is 
interesting to know that in man the convolutions are more 
numerous and extensive, and the depressions between 
them deeper, than in any other animal. The brain is 
most abundantly supplied with blood—the amount sent to 
it having been estimated as high as one'-fifth of that con¬ 
tained in the whole body, though one-tenth would be 
probably nearer the truth. 

297. Towards the- base and centre of the cerebrum, the 
surface is inflected inward, so as to form an intricate inter¬ 
nal cavity, several compartments of which are called ven 

How is the cerebrum divided ? How are the two halves connected to¬ 
gether ? What is the external appearance of each hemisphere ? Of what if 
the nervous tissue of the cerebrum composed ? How are the white and gray 
substances disposed ? How may the manner in which the two substances are 
disposed be illustrated? What is the effect of this arrangement? What 
proportion of the whole amount of blood has been estimated to be sent to the 
Drain ? What are the internal cavities called? 

10 * 



134 


CLASS-BOOK OF PHYSIOLOGY. 


tricles. They communicate with each other, and serve 
still further to increase the cerebral surfaces. It is in these 
ventricles that collections of serous fluid take place, in 
cases of what is called “dropsy of the brain,” or water in 
the head. 

298. The cerebellum is situated at the back of the head, 
below the cerebrum. It is divided into two lateral lobes, 
and, instead of waving convolutions, its surface presents 
a number of plaits with furrows between them. It is com¬ 
posed, like the cerebrum, of gray and white matter, and 
the white matter presents, on a vertical section of one of 
the lobes, a tree-like appearance, called arbor vitas (tree 
of life). 

299. The membranes which surround and protect the 
brain are three in number, and are called the dura mater , 
the arachnoid , and the pia mater . These membranes are 
also prolonged downwards, so as to form a tubular sheath 
to the spinal cord. The dura mater (hard mother) was so 
called by the old anatomists, because they supposed it to 
be the origin or mother of all the hard, firm membranes 
of the body, and the pia mater (tender mother) was also 
thus named by them, as being the origin of the soft 
membranes. 

300. The dura mater is a strong, dense, fibrous mem 
brane, which forms the external envelop of the brain, and 
is in contact with the bones of the skull, to which it 
strongly adheres. It is separated into two layers, the inter¬ 
nal of which is doubled on itself, so as to form two remark¬ 
able processes: the one, from its resemblance in shape to 
a sickle, is called falx cerebri , and is interposed between 
the two hemispheres of the brain, so that when the head 

How do they communicate with each other ? Where is the cerebellum 
situated ?—how is it divided ? Of what two substances is it composed ? 
What is the appearance of the matter when divided vertically? How is 
the brain protected ? What was the origin of the name applied to the dura 
mater and pia mater ? Describe the dura mater. What is that portion of thf 
dura mater called which divides the two hemispheres ? 



THE NERVOUS SYSTEM. 


135 


rests on one side, the uppermost hemisphere is prevented 
from pressing upon the lower. The other process is called 
tentorium cerebelli , and is extended over the cerebellum, 
so as to prevent the pressure of the cerebrum upon the 
latter when the head is in an erect position. There is also 
a smaller process, called falx cerebelli , which separates the 
two hemispheres of the cerebellum. 

301. The arachnoid (spider’s web) membrane, so called 
from its extreme thinness, lies beneath the dura mater, and 
is spread over the entire surface of the brain. It corres¬ 
ponds in its use to the serous membianes of the heart and 
other organs, and serves to keep the opposite surfaces of 
the dura mater and the pia mater, between which it lies, 
moist and smooth. 

302. The pia mater is a loose transparent web, in which 

a multitude of blood-vessels cross each other in every pos¬ 
sible direction. Minute branches of these vessels, in im¬ 
mense numbers, penetrate the brain, to which they afford 
nutriment, at the same time that they serve as a means of 
attachment between the brain and membrane. The pia 
mater follows all the convolutions, entering all the cavities 
of the brain, and is also prolonged over the spinal cord 
and the nerves, constituting one of the most important 
membranes of the body. - 

303. Twelve pairs of nerves are given off from the 
brain, and are named as follows: 1st pair, Olfactory nerves; 
2d, Optic Nerves; 3d, Motores Oculorum; 4th, Patheticus 
5 th, Trifacial nerves; 6th, Abducentes; 7th, Portio dura, 
or facial nerves; 8th, Portio Mollis, or auditory nerves, 
9 th, Grlosso-pharyngeal nerve; 10th, Pneumogastric nerve; 
llth, Hypo-glossal nerve; ljth, Spinal accessory nerve. 

304. The first pair is distributed to the inner membrane 
of the nose, and transmits to the brain the impression pro- 

What other processes are there? Describe the arachnoid membrane. De¬ 
scribe the pia mater. How many pairs of nerves are given off from the brain ? 
What are they called ? Where is the first pair distributed, and what is it? 
office?—the second ? 



136 


CLASS-BOOK OF PHYSIOLOGY. 


duced by odors. The second pair is distributed to tbe 
retina of tbe eyes, and in like manner conveys tbe im¬ 
pression of sight. Tbe third, fourth, and sixth pairs are 
nerves of motion only, and are distributed to the muscles 
which move the eyes. The fifth pair is for the most part 
a nerve of sensation only; it is divided into three branches 
—the first of which, called the ophthalmic nerve, passes 
into the orbit or cavity in which the eye is lodged, and is 
then distributed to the forehead and temples. The second 
branch, or superior maxillary, supplies the cheeks, nose, 
and upper-lip with sensitive filaments. The third, or 
inferior maxillary, which, like the spinal nerves, has also 
a motor root, imparts the power of moving to the masti¬ 
cating muscles, and gives sensibility to the parts about 
the mouth. 

305. The seventh pair is the general motor nerve of the 
muscles of the face; the eighth pair is the nerve of hear¬ 
ing, and is distributed to the internal ear; the ninth pair 
supplies the back of the mouth and pharynx, and is con¬ 
cerned in the act of swallowing; the tenth pair originates 
from the medulla oblongata, and supplies the lungs and 
air passages, as also the heart and stomach; the eleventh 
pair gives motion to the tongue; and the twelfth pair is 
concerned in respiration. All these nerves are supposed 
to contain two sets of filaments—one communicating with 
the cerebral hemispheres, and the other with the spinal 
cord. Plate XI., fig . 4, represents a section of the brain, 
showing the arrangements of these nerves. That of the 
nerves proceeding from the spinal cord is seen in Plate 
XL, fig. 1. . 

What are the third, fourth, and sixth pairs 2 What is the fifth pair 2 How 
is it divided ] Where is each branch of the fifth distributed 2 What is the 
seventh pair 2 —the eighth 2 What is the origin of the ninth pair 2 What 
organs does it supply 2 To what parts do the eleventh and twelftn give motion 1 
What two sets of filaments are all these nerves supposed to contain 2 


































































































































I 













PLATE XI. 




THE BRAIN AND SPINAL CORD. 






Figure 1.- Anterior View of the Brain and Spinal Cord, isolated from the Skeleton , 

— a, b , Right and left hemispheres of the brain, the left hemisphere covered by the arach¬ 
noid and pia-mater; the right hemisphere naked, displaying the convolutions, c, d, Right 
and left lobes of the cerebellum, e, The medulla oblongata. /, /, The spinal cord, cov¬ 
ered by the pia-mater on the right side, and showing the origins of the spinal nerves on 
the left. At/,/, are seen the two enlargements of the cord, in the neck and the loins. 
g to g, The eight cervical pairs of nerves; h to h , The twelve dorsal pairs; i to i, The five 
lumbar pairs; lc , k, The six sacral pairs. I, Lateral column of the cord, m, Posterior 
column. 

Figure 2.- A Section of the Brain and Spinal Cord, inclosed in the Skull and Verte¬ 

bral Column. — a , TJie cerebrum, b, cerebellum, c, c, The spinal cord.—The vertebrae 
are cut through, so as to display a lateral view of the cord. 

Figure 3.- The Cerebellum. — A , Anterior view. B, Posterior view. 

Figure 4.- A Vertical Section of the Brain , showing the Origins of its Nerves .— 

a, a, The cerebrum, with its convolutions, b, The cerebellum, displaying the arbor-vita; 
upon its section, c, The medulla oblongata, d, The corpus callosum, a band of fibres 
which connect’s the two hemispheres of the brain, c, The eye. /, The first pair of nerves. 
g, The second pair. h, The third pair, i, The fourth pair, j, The fifth pair. A, The sixth 
pair. I , The seventh pair, m , The eighth pair, n, The ninth pair, o, The tenth pair, 
w, The eleventh pair, q, The twelfth pair, r, Spinal nerves. 

Figure 5 .——A Horizontal Section of the Brain, showing its Interior. — a, a, Tho 
cineritious or gray substance at the outside of the brain, following the convolutions. 

b, b, The white or medullary substance at the inside of the brain, c, c, The lateral and 
middle ventricles. 


o> 





PI. XI 



Hartford .Conn. 

r. K'pHogis.Itfh..-----r ■ ' 











































































■ 




























































































- 





























































































THE NERVOUS SYSTEM. 


141 


FUNCTIONS OF THE CEREBELLUM. 

806. Much, discussion has taken place in regard to the 
functions of the cerebellum. It seems to be now agreed, 
however, by the most intelligent physiologists, that it is 
the organ which is more especially connected with motion. 
Numerous experiments have been made on living animals, 
all of which go to show that, after the removal of the 
cerebellum, the power of executing those movements 
necessary to locomotion is lost. The faculties of volition 
and sensation remain; but the power to walk, fly, or even 
stand, is uniformly lost, from the inability to combine the 
action of the muscles in groups. 

807. From facts of this character, it seems to be most 
probable that the function of the cerebellum is to harmon¬ 
ize and regulate the actions of the voluntary muscles. In 
accordance with this theory, we find that those animals 
which possess variety of motions, or muscular action in 
the highest degree, are endowed with a cerebellum cor¬ 
respondingly large. 

808. In the animals of the cat tribe, which use their 
limbs for seizing their prey, and which are capable of 
great muscular exertion, the cerebellum is larger than in 
those whose limbs are subservient to locomotion only. 
In birds, the variety of whose movements is still greater, 
it is larger than in most of the mammalia. It acquires 
jts highest development in man, as might be expected, 
from the muscular combinations necessary to maintain the 
erect position, and to perform the intricate and varied 
movements of the human hand. 

What is said in regard to the functions of the cerebellum ? How is it 
regarded by the most intelligent physiologists? What do experiments on 
living animals show in regard to the formations of the cerebellum ? What is 
most probably the function then of the cerebellum? What is said in regard 
to the development of the cerebellum in the cat tribe and in birds? In what 
class does the cerebellum acquire its highest development ? 


142 


CLASS-BOOK OF PHYSIOLOGY. 


809. The influence of each half of the cerebellum is 
directed to muscles on the opposite sides of the body; and 
it would appear that, for the right ordering of movements, 
the action of its two halves must be always mutually bal 
anced and adjusted. 

FUNCTIONS OF THE CEREBRUM. 

810. The cerebrum is the organ through which the 
phenomena of thought and intelligence are manifested. 
By its means, we reason upon the ideas excited by sensa¬ 
tions, we judge and decide upon our course of action, and 
put that decision into practice by issuing a mandate which 
is conveyed by the nervous trunks to the muscles. 

811. It is a common, but erroneous idea, that reason is 
peculiar to man, and that the actions of the lower classes 
of animals are due to* instinct alone. There can be no 
doubt that reasoning processes, exactly resembling those 
of man, are performed by many animals: such, for instance, 
as the dog, the horse, and the elephant. We must admit 
that an animal reasons when it profits by experience, and 
obviously adapts its actions to the end it desires to gain, 
especially when it departs from its natural instincts to do 
this. The presence of intelligence is also perceived in the 
differences of character found in various individuals of the 
same species. Thus, some dogs are stupid, others saga¬ 
cious, some ill-tempered, others good-tempered; just as 
there are stupid men and intelligent men, ill-tempered 
men and good-tempered men. But the actions of insects 
seem to be wholly instinctive, so that we observe no dif¬ 
ference of temper or capacity in them. 

812. ‘Birds, however, which resemble insects in many 

What is said in regard to the influence of each half of the cerebellum? 
What is the function of the cerebrum? Is reason peculiar to man? When 
may an animal be said to reason? How may we discover the presence ot 
intelligence in animals ? What example is given of different degrees of intel¬ 
ligence in an animal? What seems to be the nature of the actions of insects? 
What is said in regard to birds ? 



THE NERVOUS SYSTEM. 


143 


of their instinctive tendencies, exhibit a remarkable dis¬ 
tinction in their actions. In escaping from danger, in 
obtaining food, and in constructing their habitations, the 
actions of birds, like those of insects, are instinctive. But 
in adapting their operations to peculiar circumstances, 
birds display a variety and fertility of resource not to be 
found in insects; and birds also learn by experience, and 
may be educated, while insects observe perfect uniformity 
in all their actions. 

313. The relative amount of intelligence in different 
animals bears a pretty constant proportion to the size and 
development of the cerebral hemispheres. Size alone, 
however, does not produce all the difference. In ascend¬ 
ing from the lower to the higher animals, a marked ad¬ 
vance in the complexion of the brain is observed: the 
convolutions become more and more prominent, giving a 
proportion ably increased surface for the entrance of the 
blood-vessels, and an equally increased amount of the gray 
matter which seems to be the real centre of all the opera¬ 
tions of the organ. Still, the size of the cerebrum, com¬ 
pared with that of the spinal cord and the ganglia at its 
top, usually affords a tolerably correct measure of the 
intelligence of the animal. The same rule, holds good in 
comparing different men, if due allowance be made for the 
comparative activity of their general functions, or, in other 
words, for their differences in temperament. 

314. Thus, two men whose brain is of the same size may 
differ widely in mental vigor, because the general system 
of one performs its functions more actively and energetic¬ 
ally than that of the other. For the same reason, a man 

In what actions do birds seem to be governed by instinct, and in what b.y 
intelligence? How does the amount of intelligence in different animals com¬ 
pare with the development of the cerebral hemispheres Is all the difference 
produced by size alone ? What other circumstances are to be taken into the 
account? What is said of the size of the cerebellum, compared with that of 
the spinal cord ? How does this rule hold in regard to different men ? Why 
may two men whose brains are of the same sfce differ widely in mental vigor ? 
Under what circumstances will a large brain surpass a small one in power ? 

11 





144 


CLASS-BOOK OF PHYSIOLOGY. 


of small brain, but whose general habit is active, may have 
a more powerful intellect than another of much larger 
brain, but whose system is sluggish and inert. But of two 
men alike in temperament, and having the same general 
configuration of head, it cannot be doubted that the one 
with the larger brain will surpass the other. It is a strik¬ 
ing fact, that almost all those persons who have been 
eminent for their acquirements, or for the influence of 
their talents over their fellow-men, have had large brains. 
This was the case, for example, with Newton, Byron, 
Cuvier, Cromwell, and Napoleon. The average weight of 
the brain is about three pounds two ounces. That of 
Cuvier weighed four pounds eleven and a half ounces, and 
those of Byron and Cromwell are said (though the fact is 
doubtful) to have weighed nearly six pounds. In idiots, 
on the contrary, the brain is usually very small—in some 
instances weighing only one and a half pounds. 

315. The size of the brain may be pretty correctly 
estimated by the facial angle. This angle is obtained by 
drawing a horizontal line (c, d, figs. 49 and 50) from the 

a 



Fig. 49 .— Skull of European. Fig. 50 .— Skull of Negro. 


entrance of the ear to the floor of the cavity of the nose, 
and a second line (a, b) from the most prominent part of 
the forehead to the front of the upper jaw, so as to inter¬ 
sect the other. This line will evidently be more inclined 
to the former, and the angle formed by the two will be 

What has been said in regard to the size of the brain in men who have been 
distinguished for their talents? What examples are given of large brains? 
How is the brain in idiots ? How may the size of the brain be estimated ? 












# 


PLATE XII. 



THE NERVES 


Fig van 1.- Posterior View of the Priruipal J Verves .—The general arrangement of 

the nervous centres and the distribution of the nervous trunks are shown in this figure.— 
Tlie spinal column is laid open, so as to display the cord, with the nerves which pass from 
it. The muscles of the left side and limbs are dissected, to show the course of the princi¬ 
pal nerves. 

a, The hemispheres of the cerebrum, h, The lobes of the cerebellum, c, The spinal 
cord, d, The facial nerve, the principal motor nerve of the face, e, The brachial plexus, 
a net-work of nerves, originating by several roots from the spinal cord, and going to sup¬ 
ply the arm.—From this plexus proceed—/, the scapular nerve; g, the median nerve; A, 
the ulnar nerve; i, the musculo-spiral nerve ;j, the intercosto-humeral (nerve of Wrisberg). 
From the spinal cord proceed—the intercostal nerves, /;, k , running between the ribs; the 
nerves forming the lunbar plexus, l, from which the front of the leg is supplied; those 
forming the sacral plexus, to, which supplies the back of the leg. The chief branch of 
the sacral plexus is the great sciatic nerve, n, which divides into the tibial nerve, a, the 
peroneal or fibular nerve, p, and many other branches. The nerves seen on the right side 
of the figure, are the ramifications of the sub-cutaneous nerves, branching beneath the 
skin, in which they are finally lost. Some ef the superficial veins are also represented. 





Cl- 


PI. XII 






















































... 






V •' 


















































































. 






























► 






















































































































\ 







•• 

















































THE NERVOUS SYSTEM. 


149 


more acute in proportion as the face is more projecting 
and the forehead more retreating; while it will be nearer 
a right angle, if the forehead be prominent and the muzzle 
projecting but little. Hence, the facial angle will indicate 
the proportion which the brain bears to the face. 

316. This angle is more open in man than in any other 
animal, and it varies greatly in the various races of men. 
The difference between the facial angle of the European 
and American head, and that of the negro, is seen in figs. 
49 and 50. In the one, it is about eighty degrees, and in 
the other about seventy. In monkeys, it varies from 
about sixty-five to thirty degrees, and as we descend still 
lower, it becomes still more acute. 

CONNECTION OF THE MIND WITH THE BODY. 

317. The brain, as appears from what has already been 
said, is the connecting link between the mind and the 
body. All the organs of the body may be said to be the 
agents of the mind, inasmuch as the mind manifests itself 
through them all. Thus, the hand, the eye, the muscles 
which control the features, are all made to express, more 
or less forcibly, the varied emotions of the mind. The 
mind, too, controls, to a certain extent, the operations of 
the various functions of the bod}', to which it gives a shape 
and form in correspondence with itself. 

318. In this view, we may regard the entire body as an 
assemblage of organs for the manifestation of the mind. 
But the influence of the mind upon the body is recipro¬ 
cated by that of the body upon the mind. If the body 
can be made to suffer from the condition of the mind, the 

In what class is the facial angle more open than in all others ? How does 
it vary in different races? What is the facial angle of an European or an 
American—of a negro—of a monkey? What may we regard as the connect¬ 
ing link between the mind and the body? How may we regard all the organs 
of the body? What parts are made to express the emotion of the mind? 
What control does the mind exert over the body? What then may we 
regard the body ? How i? + he influence of the mind upon the body reciprocated ? 


L50 


CLASS-BOOK OF PHYSIOLOGY. 


mind itself is not less affected by the condition of the body . 
A single illustration will suffice to show this fact: Melan¬ 
choly, or depression of spirits from any cause whatever, 
will often produce disease and derangement of the liver; 
and, on the other hand, a derangement of the liver will 
almost always insure melancholy, though no other cause 
exists. 

319. But the intellect is not limited in its influence to 
the organic and animal functions: it also stamps itself 
upon every lineament and feature of the man. Thus, as 
we ascend in the scale of being, intelligence becomes more 
highly developed, and is marked by a more perfect organ¬ 
ization of the brain and nervous system. The nervous 
power in man is at its highest point, as is shown by the 
very liability to disease or derangement of the vital func¬ 
tions, arising from the sympathy between the physical and 
intellectual powers. The mere animal has no desires to 
gratify but those of appetite. These satiated, he has no 
anxiety for the future—no repinings for the past; he is not 
wasted by care, nor harassed by toil and disappointment. 
Man, on the contrary, is the constant subject of exciting 
and depressing influences—of functional and organic de¬ 
rangements, growing out of his complex nature. Ever 
restless, never satisfied, he is constantly on the rack of 
physical and mental torture. He consequently obtains 
the highest perfection and excellence when he obeys most 
perfectly the laws of his nature, and retains the physical 
and the intellectual in the most complete harmony of 
development. 

320. Hence, in the education of the young, the powers 
of the body and mind should be cultivated together. The 

What illustration is given to show this fact? Upon what does the intellect 
stamp itself? As wc ascend the scale of being, how is intelligence marked ? 
How is it shown that the nervous power is at its highest point in man? What 
is said in regard to the cares and anxieties of man, compared with other 
animals ? When does man obtain the highest perfection ? What should be 
observed in the education of the young ? 





THE NERVOUS SYSTEM. 


151 


mind should not be excited to such a degree as to overtask 
the brain, nor so neglected as to leave the latter without a 
proper degree of exercise. One extreme wastes the vital 
energies while yet immature; the other degrades heaven- 
born powers to a level with the brute. The injudicious 
course, so often pursued, of stimulating the intellect of 
what is called a “precocious child,” too often results in 
misery in the sufferer itself, and in disappointment to its 
unwise friends. Such children rarely fulfill the promise 
of their earliest years, and the anxious parent usually 
sees the brilliancy of their youth fade into dullness or dis¬ 
ease in after-life. 

321. During the first six or eight years, the most im¬ 
portant object in the education of the young is to develop 
the physical powers, and secure vigor and strength to the 
body. If there is a tendency to an early development of 
the intellectual powers, special care should be taken to 
restrain the exercise of the mind, till the physical powers 
shall become strong and healthy, rather than fan the flame 
already kindled till it consumes the citadel of life. 

322. In the subsequent development of the intellectual 
faculties, gradual and uniform progress is greatly to be pre¬ 
ferred to rapid strides in knowledge. They who at first 
rush furiously up the rugged path of science, are sure very 
soon to tire or fall sick by the way. Nor should the mind 
ever be confined too long on any particular study; a suit¬ 
able variety not only refreshes the mind, but affords a 
more harmonious development of all the powers. The 
young especially require variety: their minds are con¬ 
stantly on the alert for something new—something to see, 

What is said in regard to neglecting or exciting the mind What is the 
result of either extreme ? What is often the result of injudiciously s.timula- 
ting the intellect of precocious children? What is the most important object 
during the first six or eight years? What should be done if there is a tendency 
to an early development of the intellectual powers ? What is to be preferred 
in the subsequent development of the intellectual faculties? What is said in 
vegard to variety of study ? 


152 


CLASS-BOOK OF PHYSIOLOGY. 


handle, and taste—or for some new thought or truth. 
Continued application, for a great length of time, is wholly 
incompatible with their natural impulses, and fatigue very 
soon ensues when it is attempted; for the mind seeks 
variety with the same irresistible tendency that the body 
seeks change of position. 

323. In more mature years, the mind should be trained ; 
to earnest and patient thought, but not with unremitting 
toil. The best thinkers are those who possess the power 
of exerting their brains with the most energy for a limited 
period of time, and who then take liberal relaxation. 
The brain thereby exercises the power of prompt, ener¬ 
getic action; and when it acts, it is to some purpose. 
Those who keep the brain constantly at work, either be¬ 
come dull and lazy thinkers, or are prematurely worn out. 
The men who have done the most for the world and for 
the race, are men of vigorous thought and liberal exercise 
—men who take care of the body while they work the 
mind. The reason why genius so often finds an early 
grave, is because the intense exitement it creates in the 
brain soon exhausts the physical energies. 

How should the mind be trained in more mature years 1 Who are usually 
"he best thinkers? What is the effect of keeping the brain constantly at 
work ? Who are the men who have done the most for the world ? Why 
does genius so often find an early grave 1 



THE SENSES. 


153 


CHAPTER XII. 

THE SENSES. 

324. There are five senses: touch , taste , smell, hearing , 
and sight. The office of the senses is to make us acquainted 
with the material world around us, and the states of our 
own bodies. Our knowledge of the properties of matter, 
and our ideas of form, taste, odor, and sound, are all 
obtained from impressions made on the mind through 
the senses. 


SENSE OF TOUCH, 


325. The sense of touch is the most universally diffused 
of all the senses, existing in greater or less perfection in 
all animals. In some, as in man, nearly the whole exterior 
of the body is endowed with it; but in others it is limited 
to certain parts in which it is specially seated. In insects, 
the surface of the body is covered with an insensible 
shell, and the organs of 
touch are the antennae, or 
feelers. These are pro¬ 
longations from the por¬ 
tion of the head near the 
mouth; they are often of 
very great length, as in 
fig. 51, usually contain¬ 
ing a great number of 
points, and are very flex- 

7, , i_ Fig. 51.— Capricorn Beetle.— a , a, antennae. 

ible, so that they can be 

turned Ip ward any object the insect may wish to examine. 
In walking, the antennae are used almost incessantly in 
touching the surfaces over which they pass, and they seem 

How many senses are there ? What is the office of the senses ? How dc 
we obtain our ideas of form, taste, odor, and sound 1 ? Which of the senses 
is th® most universally diffused ? What is the extent in man ? How is it 
limited in other animals ? What are the organs of touch in insects 1 



154 


CLASS-BOOK OF PHYSIOLOGY. 


to be the medium of some kind of correspondence with 
each other; for ants or bees are seldom seen to meet with¬ 
out reconnoitering one another with their antennae. 

326. In fishes, the body is so covered by scales as to be 
nearly insensible. In those animals which are covered 
with hair, the sense of touch is most perfectly developed 
in those parts which are most uncovered, and are brought 
in contact with the substances on which they feed. The 
sensibility of the lips of the horse, for example, is very 
great. The carnivorous animals are usually provided with 
long hairs or “whiskers” each of which at its root is in 
contact with a filament of nerve. {Fig. 6, Pl. X.) 

327. In most of the mammalia, the lips and tongue are 
employed as the chief organs of touch. In the elephant, 
this sense is possessed very acutely by the little finger-like 
projection at the end of its trunk; and in the bat, it seems 
to be diffused over the whole membrane of which the 
wings are formed. 

328. In man, the true skin is studded with minute 
papillae, and each papilla is provided with a termination or 
a loop of a sensitory nerve. The whole external surface 
of the body is thus more or less highly endowed with this 
faculty, according as the papillae are more or less numer¬ 
ous in any particular part. In the hand, and especially at 
the extremities of the fingers, these papillas are extremely 
numerous, and the sense of touch is here most acute. 
{Figs. 4 and 5, Pl. X.) The hand is capable of a great 
variety of movements, as well as a high degree of improve¬ 
ment by education. In the blind, who learn to read with 

What is the condition of the body in fishes? Where is the sense of touch 
most perfectly developed in animals which are covered with hair ? What is 
said of the lips of the horse and the whiskers of carnivorous animals? What 
are the chief organs of touch in most of the mammalia ? In what parts is 
it possessed very acutely by the elephant and the bat ? With what is the true 
skin in man studded ? With what is each papilla provided ? Where are the 
papilla the most numerous, and the sense of touch the most acute ? What is 
said of the improvement of the hand by education ? How do the blind learn 
to read ? 


THE SENSES. 


155 


facility by simply touching the raised letters, this sense 
acquires most wonderful acuteness and precision. 

329. In animals, the sense of touch is almost wholly 
confined to the surfaces of the body, while the deeper parts 
are comparatively free from it, though not insensible to 
pain from injury or disease. In case of an ordinary cut 
or bruise, or a surgical operation, the most acute suffering 
arises from the violence inflicted on the sensitive nerves 
near the surface. Thus, a wound that is only cc sldn deep,” 
will sometimes cause quite as much immediate pain as a 
more serious injury to the deep-seated parts. The sense of 
Touch may therefore be regarded as an ever-watchful sen¬ 
tinel, placed on the exterior of our bodies to guard with 
untiring vigilance the delicate textures within. 

SENSE OF TASTE. 

330. Taste is that sense by which we judge of certain 
properties of matter—as sweet, sour, bitter, &c. Its chief 
purpose is to direct animals in the choice of food. Like 
the sense of touch, it is not excited except by the direct 
contact of particular substances; and only those substances 
which are soluble in water, or in the fluids of the mouth, 
make any impression on this organ. Substances that are 
not soluble, are said to be either insipid or tasteless. 

331. The sense of taste, in the higher animals, is con 
fined principally to the mucous membrane of the tongue, 
which is very thickly set, especially on its upper surface, 
with papillae. The papillae of the tongue have some re¬ 
semblance in structure to those of the skin, though they 
are far more highly organized. {Fig. 1, Pl. XIII.) 

332. The papillae of the tongue are of various forms 

To what parts is the sense of touch almost wholly confined in all animals ? 
Where is the pain the most acute in cases of injury? What may we regard 
the sense of touch ? What is taste ? What is its chief purpose ? How is 
the sense of taste excited ? What is said of substances that are not soluble? 
To what parts is the sense of taste chiefly confined ? What is said of the 
papillae of the tongue ?—of their form and size ? 


156 


CLASS-BOOK OF PHYSIOLOG T. 


and sizes: some are conical; others are enlarged and flat¬ 
tened at the top; some are elevated above the surface of 
the tongue; and others are imbedded beneath it. The 
fungiform papillae, which are supposed to be the special 
instruments of the sense of taste, are composed of numer* 
ous loops of capillary vessels, with a bundle of nerve- 
fibres, as represented in fig. 5, Pl. XIII. 

333. The tongue itself is made up of muscular substance, 
which accomplishes the various movements required in the 
act of mastication, and in the production of sounds. It 
possesses nearly the same structure in the other mamma¬ 
lia as in man. In birds, it is usually cartilaginous or bony 
in its texture, and destitute of nervous papillae, so that 
their sense of taste cannot be very acute. Several of 
them use their tongues for other purposes. The wood¬ 
pecker, for instance, {fig. 6, Pl. XIII.) whose tongue is 
sharp and forked, transfixes insects with it; and the par 
rot uses it to keep steady the nut or seed which is being 
crushed between its mandibles. In some reptiles, the 
tongue is large and fleshy; in others, as the serpent tribe, 
it is sharp and forked, and possessed of very great quick¬ 
ness of motion. In the frog and chameleon, it serves as 
an organ of prehension, and is darted out with great ra¬ 
pidity to catch the insects on which these animals feed. 
The tongue of the fish is generally in a more rudimentary 
state; it is fixed in the throat, and often covered with 
teeth. The tongue of the bee forms a little tube, through 
which it draws up the juices of flowers. 

334. Most of the lower animals are instinctively directed 
in the choice of their food by the sense of taste, rejecting 
what is pernicious, and selecting whatever is adapted to 

Describe the fungiform papillse 1 Of what is the tongue itself made up ? 
What is the structure of the tongue in birds ? For what other purposes is the 
tongue of some birds used 1 What is said of the tongue in reptiles ?—in ser¬ 
pents 1 —in the frog, and the chameleon 1 What of the tongue of the fish 
and the bee 1 How are most of the lower animals directed in the choice of 
their food 1 












PLATE XIII. 


ORGANS OF SENSE. 


Figure I.- The Dorsum , or Upper Surface of the Tongue .—a, Tho epiglottis, b- 

The root of tho tongue, c, c, Mucous glands, covering the root of the tongue, d , d , dj 
The large papilla?, arranged in two oblique lines, meeting at the middle of the root of the 
tongue. Spreading over the rest of the surface are seen the small papillae, in great num¬ 
bers and of different shapes and sizes. 

Figure 2.- The Inferior Surface of the Tongue. —This figure represents the lower 

side of the tongue laid open, so as to show the distribution of the nerves, a, The hyoid- 
bone, to which the base of the tongue is attached. &, &, The stylo-glossus muscles, reaching 
from the tongue to the styloid processes of the temporal-bone, c, c. Their action is to 
draw the tongue backward, d , The hypo-glossal nerve.—Minute filaments of these nerves 
are spread throughout the tongue and in its papillae. 

Figure 3.-Organ of Hearing : Vertical Section of the Organ of Hearing. — a , J, e, 

The external ear. d , Entrance to the auditory canal. /, Auditory canal, e, e, Petrous 
portion of the temporal-bone, in which the internal ear is excavated, g , Membrane of 
the tympanum. A, The tympanitic cavity or drum of the ear. (For the relative positions 
of these bones, see fig. 54, page 167.) i, Cells excavated in the temporal-bone, j, Opening 
from the ear-cavity into these cells—On the side of the cavity opposite the membrana 
tympani, are seen the fenestra ovalis and rotunda, which open into the vestibule. /, The 
vestibule, k, The Eustachian tube, rn, Semi-circular canals, w, Cochlea, o, Auditory 
nerve, p, Canal, by which the carotid artery enters the skull, q, Part of the glenoid f 03 sa, 
which receives the head of the lower-jaw. r, Styloid process of the temporal-bone. 

Figure 4.- A magnified representation of the Labyrinth , laid open , so as to display 

its Cavity.—a, The vestibule. l>, The cochlea, e, The partition by which the cochlea is 
divided into two parts, c, The fenestra ovalis. d, The fenestra rotunda. /, /, /, The 
semi-circular canals, g , Portion of the temporal-bone. 

Figure 5.- Capillary Plexus of Papilla} of Human Tongue. 

Figure 6.- Tongue of a Woodpecker. 

Figure 7.- Tongue of a Giraffe, 


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THE SENSES. 


161 


tlieir wants. Man is guided more by reason than by in¬ 
stinct, and his taste is very much influenced by habit. 
Thus, many substances that are exceedingly disgusting at 
first, become by use highly grateful. Innumerable in¬ 
stances of those acquired tastes are observed in all .ages, 
and in every state of society. Thus, epicures in various 
stages of civilization make use of meat, fish, and eggs, 
after decomposition has commenced, or after those articles 
of food are in what is called a “ripe condition;” and mul¬ 
titudes, from all classes of society, chew tobacco, the most 
disgusting of all weeds, as a sweet morsel. 

335. The susceptibility of the organs of taste ;o pleas¬ 
urable sensations, depends very much on the condition of 
the stomach, even in health. Accordingly, the relish or 
the pleasure with which we partake of any particular arti¬ 
cle of food, diminishes as hunger is appeased. If indul¬ 
gence of the appetite is persisted in beyond the actual 
demand for food, nausea or disgust will very soon super¬ 
vene, and compel even the glutton to desist. The sympathy 
subsisting between the organ of taste and the stomach, is 
an important and wise provision, informing us when a 
sufficient amount of food has been taken. 

SENSE OF SMELL. 

336. Smell is the sense by which we perceive odors. 
Certain bodies seem to possess the property of diffusing 
through the air in extreme minuteness the particles of 
which they are eomposea, and of exciting a peculiar sensa¬ 
tion in the organ of smell. Those particles which emanate 
from odorous bodies are so exceedingly minute, that many 

How is man guided 7 How do substances naturally loathsome come to be 
agreeable 7 What examples are given 7 Upon what does the susceptibility 
of the organs of taste to pleasurable sensations depend 7 What ensues if 
indulgence of the appetite is persisted in beyond the actual demand for food 7 
What is said in regard to the sympathy of the organ of taste with the stom¬ 
ach 7 What is smell 7 What properties do certain bodies seem to possess 7 
What is said of the particles which emanate from odorous bodies 7 



162 


CLASS-BOOK OF PHYSIOLOGY. 


substances do not seem to lose weight by freely imparting 
their scent to an unlimited quantity of air. Musk, for 
instance, will impart its scent to a room that is constantly 
open for many years, without any appreciable diminution 
of weight. But there are other bodies, such as camphor, 
which lose weight by loss of particles from their surface 
when freely exposed to the air. 

337. The special seat of the sense of smell is in the thin 
and delicate membrane which lines the internal surfaces 
of the nasal cavities. It is called Schneiderian membrane , 
from the man who first described its structure. 

338. The acuteness of this sense seems very nearly in 
proportion to the amount of Schneiderian membrane, or 
to the extent of surface which the nasal cavities present. 



bones, / #, h. 


339. When air charged with odorous particles passes 
over the Schneiderian membrane, in the act of ordinary 
respiration, or in the voluntary efforts of snuffing air, some 

How long will musk scent a room without any apparent loss of its particles? 
What is said of bodies which lose weight by loss of particles? Where is 
the special seat of the sense of smell ? What is the membrane called ? The 
acuteness of this sense is in proportion to what ? What is said of the size oi 
the nose in those animals which are remarkable for acuteness of smell ? How 
is the interior surface of the nose greatly increased? Explain the manner in 
which the odorous particles are made to act on the Schneiderian membrane? 


THE SENSES. 


163 


of the particles come in contact with, it, and act upon the 
delicate extremities of the olfactory nerves, with which the 
membrane is thickly set. If this membrane is either too 
moist or too dry, the odorous particles make no impression 
on it. Thus, in colds or in fevers, the sense of smell is 
almost entirely lost for the time. 

340. All animals do not perceive the same odors equally 
well. Carnivorous animals excel in detecting the odors 
of animal substances, and in tracking other animals by the 
scent, but have no apparent sensibility to the odors of 
plants and flowers. Herbivorous animals aie peculiarly 
sensitive to the latter, but their sensibility to animal odors 
is much less acute. Some herbivorous animals, however, 
possess very great acuteness of smell in regard to animal 
odors. Thus, the deer and the antelope frequently scent 
the approach of the hunter, and make their escape, unless 
he steals upon them in a direction contrary to that of the 
wind. In this class of animals, the sense of smell seems 
to be an important means by which they are warned of 
the presence of their enemies. 

341. Herbivorous animals undoubtedly require an acute 
susceptibility to the odors of plants, to guide them in select¬ 
ing their food from a variety of plants, some of which are 
highly deleterious, if not destructive, to animal life. 

342. The wonderful scent of the dog is well known. 

The certainty with which he detects the foot-steps of 
animals, long after they have passed—the facility with 
which he traces the progress of his master through crowded 
streets, recognizing the emanations which his foot has left 
among all the diversity and multitude of odorous parti- 
c ] es _i s truly astonishing. In like manner, the deer-hound 


Under what circumstances do the odorous particles fail to make any impres- . 
gion 1 ? Do all animals perceive the same odors equally well? In what do car¬ 
nivorous animals excel?—in what herbivorous? What is said of the deer and 
antelope? Of what special use does the sense of smell seem to be to this 
class of animals ? How do the herbivorous animals seem to be guided in 
selecting their food ? What is said of the scent of the dog ?—the deer-hound ? 




164 


CLASS-BOOK OF PHYSIOLOGY. 


pertinaciously pursues his victim, and follows its traces 
through the herd of its fellows, among which it vainly 
seeks for protection. 

343. Birds and fishes do not in general possess the sense 
of smell in as high perfection as quadrupeds, though they 
do not appear to be entirely destitute of it. Many insects 
are able to distinguish odorous substances at considerable 
distance; but physiologists are not agreed as to the loca¬ 
tion of the organs of smell. 

344. Like all the senses, that of smell is greatly improved 
in acuteness by education. In the blind, especially, it 
becomes next to that of touch, the sense on which they 
place the greatest reliance, and by which they distinguish 
individuals from each other. The Indians of Peru, accord¬ 
ing to Humboldt, can ascertain by the smell, in the middle 
of the night, whether a visitor be an European, an Amer¬ 
ican, an Indian, or a Hegro. Sometimes the smell becomes 
morbidly sensitive: there are those who sicken at the 
scent of cheese, or faint at that of a cat. An eminent 
French physician was exceedingly annoyed during an 
illness, in which his smell became remarkably acute, by 
the odor of copper; and after a careful search, the source 
of his annoyance was found to be a brass pin, which had 
fallen among the bed-clothes. 

SENSE OF HEAllING. 

345. Hearing is the sense by which we perceive sounds. 
The ear is the special organ of hearing, though all the 
parts which are found in the higher orders of animals are 
not essential to constitute an organ of hearing. The 
essential part of this organ is a nerve, endowed with the 
peculiar property of receiving and transmitting to the 

What is said of the sense of smell in birds and fishes ?—what of insects ? 
How may the sense of smell he improved ? How is it in the blind ? What 
is said of the Indians of Peru? What examples are given in which this sense 
has become morbidly sensitive? What is hearing? What is the special 
organ of hearing? What is the essential part of this organ? 


THE SENSES. 


165 


brain the impressions derived from the vibrations of the 
air or water with which the animal is surrounded. 

346. Thus, in some of the lower animals—as the crab, 
lobster, &c.—the ear consists of a cavity in the side of the 
head, lined with a membrane on which the nerve is dis¬ 
tributed, and filled with a watery fluid. In some, this 
cavity is completely shut in by its bony walls, and in 
others there is a small aperture covered by a membrane, 
upon which the external medium can act. This cavity, 
which corresponds with the vestibule in higher animals, is 
the whole organ in lower animals; it is the essential part 
in all, and is never omitted in the most perfect develop¬ 
ments of the organ. 

347. All other parts may be regarded as superadded to 
the vestibule, to render this essential organ more perfectly 
adapted to the wants of each group of animals. Thus, in 
the lowest fishes, a single semi-circular canal is superadded 
to the vestibule; a little higher, there are two; and in all 
other fishes, three semi-circular canals. In animals which 
live in the air, there are added other parts, which adapt 
the organ more perfectly to this element. 

348. In man, and most of the mammalia, we find the 
ear composed of three parts—the external, the middle , and 
the internal ear. 

349. The external ear is a fibro-cartilaginous appendage, 
placed on the outside of the head, to receive and conduct 
the sounds to the interior. In most of the quadrupeds, 
the external ear is very large, and capable of being turned 
in any direction at the will of the animal, as in the horse, 

Describe the ear, as found in the crab, lobster, &c. ? How is it inclosed in 
some species? With what in higher animals does this cavity correspond? 
Is this part ever omitted in the most perfect development of the organs? 
What may all other parts be regarded? What parts are added in fishes? 
What other parts are added in animals which live in the air? Of how many 
parts is the ear composed in man and most of the mammalia? What are 
these parts? Describe the external ear. What peculiarity has it in most of 
the quadrupeds ? Do men ever possess the power of moving the external ear? 


166 


CLASS-BOOK OF PHYSIOLOG 


deer, and hare. Some men also possess the power oi 
moving the external ear, though to a very limited extent. 

350. Persons who are partially deaf may make use of 
ear-trumpets, by which the vibrations of sound are col¬ 
lected from a greater extent of surface, and thereby act 
with greater intensity on the drum of the ear; or, in case 
this is destroyed, on the internal ear. 

351. The canal {fig. 3, Pl. XIII.) into which the external 
ear collects the sonorous vibrations, passes inwards until 
it is terminated by the tympanum or the membrane of 
the drum of the ear, which separates the external from 
the middle ear. This canal is about an inch in length, and 
is protected from the entrance of insects and dust by short 
hairs, which grow across the tube. 

352. In reptiles and birds, there is no external ear, and 
the tympanum is found on the surface of the head, where 
it can be easily seen, just back of the eye, as in the frog. 
In birds, it is found in a slight depression in the head, sur¬ 
rounded by a tuft of feathers. In man, it is a rough, tense 
membrane, stretched across the auditory passage, in a 
manner similar to the parchment on a drum, with its edges 
set in a bony groove. 

353. The middle ear , which is also called the tympanitic 
cavity or drum of the ear (A), is an irregular bony caVity, 
filled with air. It communicates with the external air by 
means of the Eustachian tube, which terminates in the 
back part of the throat. The use of this tube seems to be 
to produce an equilibrium between the air contained in 
the drum of the ear and the external ear. In severe colds, 

What may be made use of to collect the vibrations of sound by persons who 
are partially deaf? What effect does it have on the vibrations of sound? 
What is said of the canal into which the external ear collects the sonorous vibra¬ 
tions? How is it separated from the middle ear? What is its length? How 
is it protected from insects ? Have reptiles and birds any external ear ? Where 
is the tympanum formed in frogs?—in birds? Describe it in man. What 
other name is applied to the middle ear ? With what is it filled ? How does 
it communicate with the external air ? Where does this tube terminate ? 
What is its use ? What effect do colds sometimes have on this tube 1 


THE SENSES. 


167 


this tube is frequently obstructed, causing “ringing in the 
ear,” confusion of sound, and partial deafness. 


g & 



Fig. 53. —Bones of Fig. 54. —Cavity of the Tympanum, with 

the Ear. the bones in their places. 


354. Within the drum of the ear {fig. 3, Pl. XIII.) there 
is a very curious arrangement of small bones, which con¬ 
nect the tympanum to the membrane of the internal ear. 
These bones, which are represented in figs. 53 and 54, are 
so arranged as to form a continuous chain of bones. When 
the tympanum vibrates, they move backward and forward 
in such a manner that the slightest vibration is communi¬ 
cated to the membrane of the internal ear. In birds and 
reptiles, instead of a chain of bones, there is a single bone, 
with one extremity attached to the tympanum and the 
other to the membrane that incloses the internal ear. This 
bone can easily be seen pressing against the tympanum in 
the ear of a bird by removing the skin and feathers from 
the head. 

355. The internal ear or labyrinth is composed of three 
cavities—the vestibule , the semi-circular canals , and the 
cochlea. 

What peculiar arrangement within the ear? How are these bones ar¬ 
ranged? How do they move with the vibrations of the tympanum? What 
substitute for a chain of bones do we find in birds and reptiles ? How 
can this bone be seen in the ear of a bird ? How many cavities has the 
internal ear? 





168 


CLASS-BOOK OF PHYSIOLOGY. 


856. The vestibule (porch or entrance) corresponds with 
the simple sac that constitutes the whole organ of hearing 
in the lower animals, and is the essential part in all. It is 
separated from the middle ear by a bony partition, which 
is perforated by two small holes, called, from their form, 
foramen ovale (oval opening), and foramen rotundum (round 
opening). The first is closed by a membrane, on which 
the stapes, one of the small bones, rests, and the other by 
a membrane similar to the tympanum. 

357. The semi-circular canals are passages running, off 
from the upper part of the vestibule, in the form of three 
arched tubes. These canals are found in fishes, and in all 
animals which live in the air. Their use is supposed to 
be to assist in producing an idea of the direction of sounds, 

358. The cochlea, so called from its resemblance to a 
snail-shell, is a spiral canal, running off from the lower 
part of the vestibule. It is peculiar to those animals 
which live in the air, and has been supposed to be the 
organ by which we judge of the pitch of sounds. It also 
affords a greater extent of surface for the spreading out 
of the nervous fibres. 

359. All the above cavities of the internal ear are lined 
with a delicate membrane, on which the extremities of the 
auditory nerve are minutely distributed, and are filled 
with a watery fluid, in which filaments of the nerve are 
also found floating. These terminations of the auditory 
nerve constitute the real organ by which impressions of 
sound are received and transmitted to the brain. The 

With what does the vestibule correspond ? How is it separated from the 
middle ear ? How is this partition perforated ? How are these openings 
closed ? What are the semi-circular canals ? In what animals are those 
canals found 1 ? What is their use? From what does the cochlea derive its 
name ? What is the form and position of the cochlea ? To what class of 
animals is it peculiar ? What has been supposed to be the use of the cochlea ? 
How are the cavities of the internal ear lined ? What is distributed on this 
membrane? With what are these cavities filled? What constitutes the 
real organ by which impressions of sound are received and transmitted ? How 
ere the vibrations of sound communicated to the nerve ? 


THE SENSES. 


160 


vibrations of sound are communicated to the nerve through 
the medium of a watery fluid. 

360. Sound travels through the air at the rate of about 
twelve and a half miles in a minute; through water, its 
velocity is four times greater; and the intensity of the 
vibrations of sound in air and water are in about the same 
proportion.* Hence, the impressions of sound on the 
nerves which are the immediate seat of hearing are much 
more intense in the watery fluid, which fills the cavities 
of the internal ear, than they could be if those cavities 
were filled with air. For the same reason, animals which 
live in the air require an apparatus for hearing more com¬ 
plicated than those animals which live in the water. Ac¬ 
cordingly, we find in those animals which live in the air, 
the addition of just those parts that would communicate 
the vibrations of sound from the air to the fluid of the 
internal ear with the greatest intensity. Thus, a tense 
membrane, like that of the drum of the ear, with air on 
both sides, is better adapted than any other animal struc¬ 
ture to receive the vibrations of the air; and the arrange¬ 
ment of the bones which connect this membrane with that 
of the internal ear, is equally well fitted for the office of 
conducting those vibrations to the fluid of the internal ear. 

361. Still, the faculty of hearing will not be entirely 
lost if the drum of the ear is destroyed, so that the vibra¬ 
tions of sound act directly on the membrane of the internal 

At what rate does sound travel through the air? What is its velocity 
through water ? What advantage then is gained by the nerves receiving 
impressions through water instead of air ? Why do animals which live in air 
require an apparatus more complicated than those which live in water? 
What parts do we find added in those animals which live in air ? What is 
said in regard to the adaptation of the tympanum and the bones which con¬ 
nect it to the internal ear to receive the vibrations of the air? Will the 
faculty of hearing be entirely lost if the drum is destroyed ? How will the 
hearing be affected by its loss? 


* The difference in the intensity of the vibrations of sound in air and 
water may be easily perceived by striking two stones together with 
equal force—first in the air and then under water, with the head immersed. 






170 


CLASS-BOOK OF PHYSIOLOGY. 


ear, though it will be greatly impaired, rendering the 
individual partially deaf. 

362. The faculty of hearing may be very much increased 
in acuteness by cultivation; but this increase depends 
rather upon the habit of attention to the faintest impres¬ 
sions made upon the organ, than upon any change of the 
organ itself. Thus, the watchful Indian, recognizes foot¬ 
steps, and can even distinguish the tread of a friend from 
that of a foe, while his white companion, who lives among 
the busy hum of cities, is unconscious of such slight 
sounds. Yet the latter may be a musician, capable of dis¬ 
tinguishing the tones of all the different instruments in a 
large orchestra—of following any one of them through the 
part which it performs—and of detecting the least discord 
in the blended effects of the whole—effects which would 
be to the Indian only a confused mass of sound. 

SENSE OF SIGHT. 

363. Sight is the sense by which we are enabled to 
perceive luminous impressions; and through these we be¬ 
come acquainted with the form, size, color, and position 
of objects that transmit or reflect light. 

364. The eye is the organ of sight. It consists essen¬ 
tially in an instrument capable of making a distinct picture 
of surrounding objects on the expanded surface of the 
nerve of sight. 

365. Some of the inferior animals, such as the leech, 
seem to be guided in their movements by certain dark 
spots on their surface, supposed to be rudimentary eyes, 
though no fully developed eyes have as yet been dis¬ 
covered. In some of the star-fishes those eye-spots are 
found at the extremity of the rays, as in fig. 1 , Pl. XYI. 

How may the faculty of hearing be increased in acuteness? Upon what 
does this increase seem to depend? Whafexamples are given of the habit 
of attention? What is sight? What is the organ of sight? In what does 
it consist essentially? How do some of"the inferior animals seem vo be 
guided in their movements ? 





















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ORGANS OE VISION—THE EYE. * 

Figure 1.- The Left Eyeball , showing the Posterior Surface of the Retina.— c, A 

small transparent spot, situated near the optic nerve, called the foramen of Soemmering-, 
surrounded by a yellow halo, the limbus luteus. by The optic nerve, cut off at its entrance 
into the retina, c, The central artery of the retina, d, d, Ramifications of the artery on 
the inner wall of the retina, seen through the outer layers. 

Figure 2.- The Globe of the Eye , magnified, and seen in front. —This figure repre* 

sonts the second or choroid coat, the sclerotica being removed, a, The pupil, b, The iris, 
c, c, The choroid membrane, d, d, The ciliary nerves, running from every part of the cir> 
cumference towards the iris, e, e, The ciliary arteries. 

Figure 3.- The Globe of the Eye , seen in the same view .—The iris i*s removed, in 

order to display the ciliary processes, and their position in regard to the lens. The ciliary 

nerves and arteries are the same as in fig. 2. 

*. 

Figure 4.- The Anterior Half of the Globe of the Eye, seen from behind. — The lens 

and the vitreous humor are removed, a The pupil, b, b, The posterior surface of the 
iris, called, from its dark grape-like color, uvea, c, c, The ciliary processes, d, d, The 
internal surface of the choroid and sclerotic. 

Figure 5.- The Posterior Half of the Globe of the Eye, showing its internal surface. 

-ay ay The cut edges of the sclerotic, choroid, and retina, by by The internal surface of 
the retina, c, The foramen of Soemmering, d, The optic nerve, e, Branches of the 
central artery of the retina. 

Fioure 6.- The Fibres of the Iris, detached. — a, The pupil, b , The circular fibres at 

the central margin of the iris, by the action of which the pupil is diminished or enlarged. 

Cy c, The radiating fibres, which proceed from the external border of the circular fibres. 

Figure 7.- A Portion of the Pigment Membrane of the Choroid Coaty highly magni¬ 

fied. —It is seen to consist of regular six-sided plates, the tissue of which is filled with 
grains of coloring matter. 

Fioure 8. - Compound Eyes of the Bee, highly magnified, showing the Division into j 

Facets, and also the Conical Shape of each separate Portion. — A, Facets still more highly j 
magnified. B, The seme with hairs growing between them. 

Figure 9.- A, Front View of the Crystalline Lens. 


Figure 10.- Side View of the Crystalline Lens. — a , Its anterior and least convexity. 

by Its posterior and greatest convexity. 

Figure 11.- The Crystalline Lens , after being immersed in boiling water. —The lines 

on its surface show its division into three parts. 

Figure 12.- The Three Segments of the Crystalline Lens. —The faces of the segments 

show the concentric layers of which it is composed (like the coats of an onion). The 
nucleus, or central portion of the lens, is seen on one of the segments, and on the other 
two are corresponding depressions. 







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THE SENSES. 


175 


366. Most insects are furnished with compound eyes, 
which consist of several hexagonal facets, (Jig. 8, Pl. XIY.) 
united together in such a manner as to form a large, dark- 
colored protuberance on each side of the head. Each of 
these facets is an eye in itself. In some insects, these 
facets are exceedingly numerous. In the eye of a butter- 
fly> 17,000 have been counted; in some species of beetle, 
25,000; in the common horse-fly, 4,000. These numer¬ 
ous eyes, no two of which have the same direction, seem 
to compensate for the inability of the insects to move the 
head without moving the whole body, since they are pro¬ 
vided with an eye in every direction. 

367. Spiders are furnished with from six to fourteen 
eyes, situated on the most prominent part of the back, 
instead of on the sides of the head. {Fig. 3, Pl. XYI.) 

368. In the snail and some other mollusks there are 
only two eyes, situated on or near the tip of a flexible 
stalk—the tentacula, {fig. 2, Pl. XYI.) which can be 
extended in any direction at the pleasure of the animal. 
In lobsters and crabs the eye is placed at the extremity of 
a long tube, which can be moved in various directions, 
and extended or withdrawn. 

369. In all the higher animals there are only two eyes, 
which are constructed on the same general plan, with some 
variation in the form of particular parts, adapting the eye 
to the medium with which different animals are surrounded. 

370. The form of the eye is nearly globular in all, and 
placed in a bony socket (the orbit) in the head. The orbit 
is lined with a cushion of fat, on which the eye rests and 
rolls with very great ease. When a person becomes very 

With what are most insects provided ? Of what are those compound eyes 
made up? What is each facet? How numerous are these facets? How 
many in the eye of a butter-fly—in the beetle ? What seems to be the use 
of so large a number? With how many eyes are spiders provided? How 
many eyes are there in the snail, and how are they situated? How is the eye 
placed in crabs and lobsters ? How many eyes are there in all the higher 
animals ? What is the form of the eye, and how is it placed ? How is the 
orbit lined ? 





176 


CLASS-BOOK OF PHYSIOLOGY. 


mucn emaciated, this cushion of fat is gradually absorbed, 
allowing the eye to recede into the orbit. 

371. The eye is admirably protected against insects, j 
dust, and other foreign substances, by the eye-brows, eye¬ 
lids, and eye-lashes. 

372. In birds and reptiles there is a thin transparent 
membrane which is drawn across the eye by a muscle 
that passes through a loop in the membrane, {fig . 4, Pl. 
XYI.) This nictating membrane is so transparent as not 
to prevent the power of vision, while it protects the eye 
from too strong light, and guards it against foreign bodies. 

373. The horse is provided with a beautiful contrivance 
for protecting the eye, called the haw. It is a triangular¬ 
shaped cartilage, admirably adapted to the convexity of 
the eye, and so arranged that it is made to sweep across 
the eye at the will of the animal, and shovel up any dust 
or insect that may fall upon it. 

374. The anterior surface of the eye is covered by the 
conjunctiva—a thin mucous membrane, which is reflected 
upon the lids, so as to form their internal surface. 

375. The conjunctiva is constantly moistened by the 
mucus from its surface, and by the tears that are secreted 
in the lachrymal glands, and poured upon the inner sur¬ 
face of the upper lid by seven or eight tubes. The lach¬ 
rymal gland {fig . 2, Pl. XY.) is situated at the upper or 
outer angle of the orbit. It is continually pouring out a 
watery fluid, which moistens the globe of the eye, and 
keeps it free from impurities. This secretion is increased 
by mental emotion, and by irritation of the eye. The j 
tears pass out from the eye by two lachrymal ducts, which 

What takes place when a person becomes very much emaciated ? How it, | 
the eye protected against insects, dust, &e. ? What membrane is there in 
birds and reptiles? How is it drawn across the eye? How does it protect 
the eye without preventing sight ? With what is the horse prc vided ? De¬ 
scribe the haw ? How is the interior surface of the eye covered ? How is 
the conjunctiva moistened? Where is the lachrymal gland situated ? What 
is continually pouring out from this gland ? How is this secretion increased ? 
How do the tears pass out of the eye ? 



























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PLATE XV. 


$ 


ORGAN OF YISION.—THE EYE. 


Figure 1.- Both Eyes , with their Muscles , as they appear upon a horizontal section 

through the orbits, immediately above the eyes—as if the upper part of the head were 
removed, as far down as the top of the eyes, the observer looking at them from above. 
They are represented in this position, in order to show clearly the situation and action of 
the superior oblique muscle, and also the crossing or decussation of the optic nerve. The 
letters of reference indicate the same parts in figures 1 and 3. 

a, The optic nerve, a, figure 1, The chiasma or commissure of the optic nerve, whence 
each nerve extends forward and outward, passes into the eye at t, and becomes continuous 
with the retina, b , The common oculo-motory nerve, which is distributed to five of the 
muscles of the eye. lc, Trunk of the fifth pair, a branch of which constitutes the ophthal¬ 
mic nerve, and gives sensibility to the different parts of the eye.—The distribution of this 
nerve is seen in the left eye in figure 1. I, Artery of the eye. c, The elevator muscle of 
the upper eyelid, d, The superior rectus, or elevator of the eye. e, The inferior rectus, 
or depressor of the eye. /, The internal rectus. g, The external rectus. h, figure 1, The 
superior oblique muscle, in, Its pulley, i, figure 3, The inferior oblique muscle. In figure 
1, parts of several of these muscles are removed, in order to display the others distinctly. 

Figure 2.- The Lachrymal Apparatus. — a , The lachrymal gland, b, b. The lachry¬ 

mal ducts, which collect the tears, and transmit them to the lachrymal sac, c, whence they 
pass into the cavity of the nose. 

Figure 3. - The Right Eye , with its Muscles, displayed in the cavity of the orbit, on 

the vertical plane of a section corresponding to the middle of the arch of the oyebrow:— 
that is, as if the right side of the head were removed, as far as the middle of tho right eye¬ 
brow, leaving the eye in its place, to be seen from the right. 









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EL. XV. 


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THE SENSES. 


is: 


commence in a small opening in the edge of each lid, near 
the corner of the eye, and unite to form the lachrymal sac 
that lies upon the side of the upper parts of the nose, 
From the lachrymal sac a canal passes down to the interior 
of the nose, where the tears pass off in vapor with the breath. 

876. The walls of the eye are composed of three coats: 
the sclerotic , the cornea , and the choroid coat. Its interior is 
occupied by three humors: the aqueous, the crystalline, 
and the vitreous. 

377. The sclerotic , (Jig. 55,) so named from its firmness 
and density, constitutes about four-fifths of the globe of 
the eye. It is a tough fibrous structure, admirably adapted 
to protect and support this delicate organ. 


— i 

v 

c 


Fig . 55 .— Interior of the Eye. Fig . 56.—Section of the Eye. 

c, cornea; s, sclerotic; s’ portion of the sclerotic turned back to show the subjacent parts; 
cb, choroid; r, retina; n , optic nerve; ca, anterior chamber; i , iris; p , pupil: cr, crys¬ 
talline lens; cp, ciliary processes; v, vitreous humor; b, b, conjunctiva. 

378. The cornea (c, fig. 55) is a dense transparent struct¬ 
ure, convex in front and concave posteriorly. It resem¬ 
bles a watch-glass in form, and is received into a circular 
groove in the margin of the sclerotic, in the same manner 
that a watch-glass is inserted into the case. It occupies 
about one-fifth of the front part of the eye, and projects 
forward beyond the sclerotic. In some individuals and 

Where is the lachrymal sac situated, and how do the tears escape from it? 
Of what are the walls of the eye composed ? How is its interior occupied? 
Describe the sclerotic. Describe the cornea. How is it received into the 
sclerotic ? What portion of the eye does it occupy ? What is said in regard 
to its prominence at different periods of life and in different animals ? 








182 


CLASS-BOOK OF PHYSIOLOGY. 


in some animals it is more prominent than in others, and 
it is also more prominent at some periods of life than at 
others. In fishes, and in some water-birds, it has only a 
slight projection forward, as represented in figs. 5 and 6, 
Pl. XYI. 

879. The choroid coat , (jA, fig. 55,) which is a thin, 
delicate structure, consisting mostly of blood-vessels and 
nerves, lines the interior of the sclerotic. The internal 
surface of the choroid is covered by a layer of black pig¬ 
ment cells. {Fig. 7, Pl. XIY.) 

H 880. The aqueous humor, which occupies the anterior 
chamber of the eye, {fig. 56,) is nearly pure water. It 
gives prominence to the cornea, causing it to be more or 
less convex, according to the amount of this fluid. 

881. The vitreous humor, which resembles thin jelly or 
melted glass in consistence, occupies the greater part of 
the globe of the eye behind the iris. 

882. The crystalline humor resembles thick jelly or 
soft gristle. It has the form of a double-convex lens, 
whence it has received the name of crystalline lens. In 
those animals which have only slight projections of the 
cornea, it is nearly spherical. {Figs. 5 and 6, Pl. XYI.) 
It is suspended in its place by the ciliary process, {fig. 8, 
Pl. XIY.) a set of little bands from the choroid coat. 

883. The aqueous and vitreous humors are separated 
from each other by the iris, {fig. 2, Pl. XIY.) a kind of 
curtain, which divides the anterior from the posterior 
chamber of the eye. The iris receives its name from the 
great variety of its colors. It is perforated in the centre by 
an opening, called the pupil. {Fig. 2, Pl. XIY.) In man, 
this pupil is round, and dilates or contracts according to 
the amount of light and the sensibility of the optic nerve. 

What fluid occupies the anterior chamber of the eye ? How does it affect 
the form of the cornea ? Describe the vitreous humor—the crystalline humor. 
What is the form of it? How is it suspended in its place? How are the 
aqueous and vitreous humors separated from each other ? From what does 
the iris receive its name ? What opening has the iris in the centre ? What 
is the form of the pupil in man? 


THE SENSES. 


188 


When the light is very strong, it is but a speck, and 
enlarges to nearly half the size of the iris in the dark. In 
birds, especially in owls, its motions are more free and 
extensive than in man. 

384. The blackness of the pupil is owing to the dark 
color of the internal surface of the choroid. In Albinoes, 
which are destitute of coloring matter, the pupil, as well 
as the iris, are a bright red, from the numerous capillary 
blood-vessels of the choroid. In many quadrupeds—as 
the ox, the lion, and the cat—a portion of the surface of 
the choroid is covered with a bluish layer of bright metallic 
lustre, by which the light is brilliantly reflected, when the 
eye is seen in certain directions, causing the eyes to appear 
in an obscure light like two balls of fire. 

385. In animals whose range of vision is required to 
extend widely in a horizontal direction—as in the deer, 
cow, &c.—it is lengthened horizontally, so as to give a 
wide side-view. In the carnivorous animals—as the lion / 
cat, &c.—which watch their prey in situations either above 
or below them, the pupil is elongated vertically. 

386. Inside of the choroid coat, and at the back part of 
the eye, is the retina, which consists of a delicate film of 
nervous fibres, spread out from the optic nerve as-soon as 
it has passed through the sclerotic and choroid coats. 
V387. The globe of the eye is moved by six muscles— 
four recti or straight, and two oblique —all of which are 
lodged in the orbit. The superior rectus or straight 
muscle {fig. 3, Pl. XV.) rolls the eye upward, and the 
inferior rectus turns it downward. The internal rectus 
rolls the globe inward, or toward the nose, and the external 

How does it vary in size ? To what is the blackness of the pupil owing? 
What is the color of the pupil and iris in albinoes? What peculiar appearance 
has the eye in many quadrupeds? What is the form of the pupil in grazing 
animals?—in carnivorous animals? W^hat is situated inside of the choroid 
coat? Describe the retina. How is the globe of the eye moved? How 
does the superior rectus move the eye ?—the inferior rectus ?— the internal 
rectus?—the external rectus? 



184 


CLASS-BOOK OF PHYSIOLOGY. 


rectus turns it outward. The superior oblique, a very 
remarkable muscle, has its origin at the back of the orbit, 
passing forward through a little cartilaginous pulley, and 
then turning backward, to be inserted into the sclerotic 
coat. The direction of its action is thus changed, like 
that of a rope which is passed through a block in an 
ordinary pulley. The use of this muscle is to roll the eye 
downward and inward. The inferior oblique turns it 
upward and outward. 

888. The coats and humors of the eye seem admirably 
adapted to modify the rays of light, which fall on the 
nerve of sight in such a manner as to make the impression 
clear and distinct. All the parts of the eye are constructed 
in such strict accordance with the laws of light, that it 
excels all other optical instruments in perfection and ac¬ 
curacy. Human skill has thus far effected only an imper¬ 
fect imitation of the instrument designed by Infinite 
Wisdom. 

389. It is well known that when the rays of light pass 
obliquely from the air through a dense medium, they are 
refracted or bent out of their course, as in fig. 7, Pl. XVI., 
and that the refraction is in propor¬ 
tion as the rays fall more or less 
obliquely. Thus, if a piece of money 
be placed in a cup {fig . 57) in such 
a position that the side of the cup 
will just hide the money from sight, 
and then let the cup be filled with 
water, the money will be distinctly 
visible from the refraction of the rays of light. For the 

Describe the superior oblique ? What is the use of this muscle? In what 
direction does the inferior oblique turn the eye? To what do the coats and 
humors of the eye seem adapted? How does the eye compare with optical 
instruments ? How are the rays of light affected by passing obliquely from a 
rarer to a denser medium ? The refraction is in proportion to what ? What 
examples are given, illustrating the refraction of the rays of light in passing 
from air to water ? 


cl 





























* 






















ORGANS OF VISION—THE EYE. 


PLATE XVI. 



Figure 1.- Eye-spots of a Star-fish, at the extremities of the radii. 




Figure 2. - Eyes of a Snail, on the extremities of the tentaculae. 

Figure 3. - Eyes of a Spider, on the anterior part of the back. 

Figure 4.- Nictating Membrane of a Bird. —A, Nictating membrane, covering ouo* 

half the surface of the eye. B, The muscles by which the membrane is drawn across the 
eye. The muscle a forms a loop at b, through which the muscle c acts as through a pulley 
by its tendon d, which is inserted into the edge of the nictating membrane at e. 

Figure 5.- Eye of a Fish, with very slight convexity of the cornea, and the lens 

nearly spherical, so as to compensate for the want of refractive power in the anterior 
part of the eye. 

Figure 6. - Eye of a Duck, with a similar formation. 

Figure 7. - Refraction of Light. — a, The ray of light falling obliquely on a dense me¬ 

dium at b , is refracted to c, instead of pursuing its original course to d; when it passes into 
a rarer medium again at c, it is again refracted in a new course down to d, instead of/. 

Figure 8.- The Lenses. — a, Single convex lens, b, Single concave lens, c, Double 

convex lens, d, Double concave lens, e, Concavo convex lens. 

Figure 9.- Short-sightedness —The image formed in front of the retina. 

Figure 10. - Long-sightedness —The image formed back of the retina. 

Figure 11. - Eye of a Lynx. — a, Ciliary process, by which the lens, b, is moved 

backward and forward, to adapt it to different distances. 

Figure 12. - Eye of an Eagle. — a, Fan-like muscle, attached to the lens, to change 

its position. 

Figure 13. - Eye of an Owl, surrounded by a kind of bony case, which causes the 

anterior portion of the eye to become more, and the posterior portion less convex, when¬ 
ever the eye is drawn back into the socket. By this means the focal distance is changed, 
find the eye adapted to different distances. 





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THE SENSES. 


189 


game reason an oar or a stick, when partly immersed in 
water, will appear bent in proportion to its obliquity. 

390. The rays of light which fall upon the "cornea of 
the eye are refracted towards the pupil, both by the dens¬ 
ity of the cornea and aqueous humor, and by the con¬ 
vexity of the cornea, which causes the rays to fall on it 
more obliquely. 

391. After passing through the pupil, the rays of light 
continue to be refracted by the crystalline lens and vitre¬ 
ous humor, so that they meet in a focus on the retina, 
where a complete inverted image or picture of the object 
is thus formed. This is 
shown in fig. 58, where, 
for the sake of conve¬ 
nience, two rays, only are 
represented as issuing 
from each of the two extremities of an object, a, c. Those 
rays cross each other in the middle of the eye—those 
from a being brought to a focus at b, and those from c at 
d; and as all the other rays are refracted in the same man¬ 
ner, a complete inverted picture of the object is formed at 
the back of the eye. 

392. The inverted image may be easily seen by remov¬ 
ing the fat and muscle from the eye of a white rabbit, and 
bringing a lighted candle in front of it, when an inverted 
image may be distinctly seen on the retina through the 
transparent coat of the sclerotic; or it may be seen by 
removing the sclerotic from the back part of the eye of a 
sheep or an ox. In either case, the eye should be fresh, 
as the cornea and humors soon lose their transparency, 
and the image becomes indistinct.* 

How are the rays of light refracted towards the pupil 1 flow are the rays 
of light affected by the crystalline lens and the vitreous humor ? What is the 
position of the image on the retina ? Describe Figure 53. How may the 
inverted image be seen 1 

* To show the retina of the eye, clip off the muscular and adipose 
substance about it, then describe with the knife a circle about the 



Fig. 58. 









190 # CLASS-BOOK OF PHYSIOLOGY. 

393. The black pigment, which is situated in the inter 
nal surface of the choroid, and immediately behind the 
retina, absorbs the rays of light as soon as they have passed 
through the retina, and prevents them from being reflected 
from one part of the eye to another, causing confusion and 
indistinctness in the picture. The black pigment also 
diminishes the intensity of the impression of light on the 
retina. In Albinoes, (in whose eyes the pigment is defi¬ 
cient,) vision is not only extremely imperfect, but the 
strong sunlight is even painful to the eye. Hence, Albi¬ 
noes can see most clearly when twilight comes on, or 
during cloudy days, or by moonlight. 

394. The ordinary forms of defective vision, known as 
short-sightedness and long-sightedness, are caused by 
defects in the refractive power of the eye. 

395. In short-sightedness, the refractive power is too 
great, causing the rays to be brought to a focus forward 
of the retina, unless the object be held very near the eye, 
so as to increase the angle at which they fall on the cor¬ 
nea. {Fig. 9, Pl. XYI.) In most cases of. short-sighted¬ 
ness, the cornea is too convex from an excess of the 
aqueous humour. 

396. Short-sightedness is frequently caused in students 

What is the use of the black pigment on the internal surface of the choroid ? 
How does the light affect the eye in Albinoes ? How are short and long¬ 
sightedness caused? What is the defect in short-sightedness? What is the 
Jorm of the cornea in short-sightedness ? How is it frequently caused ? 

entrance of the optic nerve that shall include one-fourth of the ball of 
the eye; holding the eye in the thumb and fingers of the left hand, 
gradually and carefully cut through the sclerotic to the choroid coat, at 
a single point in the circle already described, and then complete the dis¬ 
section in water by carefully insinuating the sharp point of the scissors 
between the coats, and clipping round the circle. The slight attach¬ 
ment of the choroid to the sclerotic may now be separated with the 
back of the knife till the detached portion of the sclerotic can be clipped 
off, leaving the nerve entire. The dissection is now complete; and, if 
well performed, inverted images of objects can be seen on the retina aa 
in life. 




THE SENSES. 


191 


And artisans by the habit of holding objects near the eyes, 
till they adapt themselves to a short focal distance, and it 
may be remedied by perseverance in the opposite practice. 
Thus, sailors, from the long habit of using their eyes in 
search of distant objects, acquire the ability of recognizing 
objects at a distance that would be unobserved by a 
landsman. 

397. If short-sightedness has continued from birth, it 
can seldom be remedied, except by the use of concave 
glasses, the curvature of which compensates for the excess 
of the convexity of the eye. If the glasses used be toG 
concave, they will increase the difficulty; while those that 
are not quite concave enough, will have a tendency to 
remedy it. If glasses can be dispensed with, or if they 
are changed for those less concave every few years, the 
difficulty will gradually diminish, till, in advanced life, 
the eye assumes the natural form. 

398. In long-sightedness, {fig. 10, Pl. XYI.) which is 
commonly met with in persons in advanced life, the re¬ 
fractive power of the eye is not sufficient to bring the rays 
to a focus on the retina, but back of it, unless the object 
be held at a long distance from the eye. At this period 
the eye is not sufficiently convex, from the decrease of its 
fluids. This difficulty may be remedied by perseverance 
in the habit of holding objects as near the eye as possible, 
or wearing spectacles with convex glasses, which shall 
compensate for the deficiency of the convexity of the eye. 

399. The eye is the most delicate of the organs of sense, 
and is more liable to disease than any other. In many 
persons the conjunctiva is exceedingly sensitive, and 

How may short-sightedness be remedied ? What power do sailors acquire 
by the habit of viewing objects at a distance ? What kind of glasses may be 
used to remedy short-sightedness ? What will be the effect of using glasses 
that are too concave ?—not quite concave enough to compensate for the con¬ 
vexity of the eye ? How does the eye gradually return to its natural form * 
What is the cause of long-sightedness? What change in the eye diminishes 
its convexity ? How may the difficulty be remedied ? What is said in regard 
to the liability of the eye to beccrne diseased ? 




192 


CLASS-BOOK OF PHYSIOLOGY. 


becomes inflamed from very slight causes. Exposure to 
dust, to wind, or to a strong light, not unfrequently induces 
severe inflammation. The optic nerve is also liable to 
serious injury from exposure to a strong light, from too pro¬ 
tracted application to study, or from using the eyes with 
insufficient light. Disease of the eyes may be prevented by 
a careful regard to their strength, by refraining from their 
use in improper light, and by affording them rest as soon 
as a sense of fatigue begins to be experienced. Moderate 
ablution at bed-time, and liberal washing in cold water on 
rising in the morning, will be found of great service in 
promoting strength and vigor. 


CHAPTER XIII. 

ANIMAL MOTION. 

400. The power of voluntary motion is characteristic 
of all animals. 

401. The organs of voluntary motion are the bones and 
muscles. 

402. The bones constitute the frame-work of the body 
and give strength and firmness to the entire organization 

403. The muscles form the greatest part of the mass of 
the body, and constitute what is commonly known as flesh 
or lean meat. 

404. The principal hard parts in animals are shells, 
crusts, and bones. Shells are almost destitute of animal 
matter, being nearly the same in composition as a piece of 
marble. Crusts, such as the covering of the lobster, con¬ 
tain a considerable quantity of animal matter, though less 
than is found in bones. 


What parts are liable to become inflamed or to be injured by improper use ? 
What causes induce disease ? How may disease be prevented I What power 
is characteristic of all animals'? What are the organs of voluntary motion? 
What do the bones constitute ?—what the muscles ? What are the principal 
lard parts in animals ? What is the composition of shells ?—of crusts ? 










» 









PLATE XVII 


ORGANS OF MOTION.-THE BONES. 


Figure 1.- Front View of the Human Skeleton. —At the right half of this figure, the 

bones are represented in their natural connections, and divested of all covering. At tho 
left side, the joints are covered by their ligaments. The outer lines show the form of the 
body when covered with flesh. 

The Head. —a, The frontal-bone. J, The parietal-bone. c, The temporal-bone, e, The 
superior maxillary-bone. /, The malar-bone, g, The nasal bones. A, The vomer, i, The 
inferior maxillary-bone, k, The orbits. /, Z, Sutures. 

The Trunk. — 1, 1, The spinal column. 2, The sternum. 3, 3, The ribs. 4, The os 
innominatum, or haunch-bone. 5, The sacrum. 

The Superior Extremities. — G, The clavicle. 7, Acromion process of the scapula, 
which articulates with the clavicle. 8, The humerus. 9, The elbow-joint. 10, The radius. 
11, The ulna. 12, Bones of the carpus. 13, Bones of the metacarpus. 14, The phalanges. 

The Inferior Extremities. —15, The hip-joint. 16, The femur, or thigh-bone. 17, 
The patella. 18, The tibia. 19, The fibula. 20, Bones of the tarsus. 21, Bones of the 
metatarsus. 22, Bones of the toes. On the left side of the figure, l indicates the ligaments 
of the shoulder, m , Ligaments of the elbow, «, Ligaments of the wrist. s, Ligaments 
of the hip-joint, o , Ligaments of the knee, and tendon of the extensor muscle of the leg. 

р, Ligaments of the ankle, q, Large vein and artery of the arm. r, Large vein and artery 
of the leg. 

Figure 2.- A Bone deprived of its earthy portion ly maceration in a dilute acid, and 

tied in a knot to show its flexibility. 

Fioure 3. - A Section of the Femur , showing its cancellous structure. 

Fioure 4.- A Dorsal Vertebra. —a, The body of the vertebra, b , The spinal foramen 

с, c, Articulating processes, d , d, Transverse processes, c, Spinous processes. 

Figure 5.- A Lumbar Vertebra , to show the greater thickness and strength of its 

body and processes. 

Figure 6.- The Lower Jaw. — a, The condyle, which articulates with the temporal- 

bone. A, The coronoid process, c, The ramus. 

Figure 7.- Vertebra of a Fish. — A , End view. B, Side view of the same. 

Figures 8 and 9.-These figures are designed to show the minute structure of bone. 

Figure 8 represents a cross-section of bone, highly magnified, a, a, Orifices of small tubes, 
called, from their discoverer, Haversian canals. They usually run in the direction of the 
length of the bone, the membrane lining the hollow of which is prolonged into their canals. 
This membrane contains innumerable small blood-vessels, and the interior of the bone 
is thus supplied with blood. Around each of the Haversian canals are seen concentric 
circles of some small dark spots, which are found to be flattened cavities or bone-cells, 
from which proceed numerous minute tubules. These open into the sides of the Haver¬ 
sian canals, and communicate from one bone-rcell to another, thus transmitting the 
nourishment with which they are supplied by the blood-vessels throughout the substance 
of the bone. Figure 9, represents a longitudinal section of bone, highly magnified, showing 
the Haversian canals seen lengthwise, their connexion with each other, and the direction 
of the bone-cells. These figures are from HassaWs Microscopic Anatomy. 




PL.XVII 






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ANIMAL MOTION. 


197 


405. At first, bones exist in a state of cartilage, and are 
gradually converted into bone by a deposition of phos- 

k pbate and carbonate of lime. 

406. The lime of the earthy portion of the bones is 
continually increasing till old age, while the animal por¬ 
tion is gradually diminishing. In children, the animal 
matter constitutes about one-half; in adults, one-fifth; and 
in old age, one-eighth of the whole composition. 

407. In children, the bones are soft and flexible, and 
admirably adapted to sustain the numerous falls and acci¬ 
dents, to which they are liable, without injury. At this 
age, the bones are not easily broken, though they are bent 
and twisted from their natural form. Thus, infants are 
not unfrequently made “bow-legged,” by efforts to bear 
their weight on their limbs before they have acquired the 
proper proportion of earthy matter to give them the requi¬ 
site strength. If not encouraged by parental ambition, 
nature does not incline the young infant to make the effort 
to stand or walk until the period when the bones have 

j become quite stiff and hard. 

408. The bones do not arrive at their perfect state until 
about the twentieth year. Previous to this period, the 
form of the bones maybe easily changed by improper 
habits. Indeed, some change may be effected in many of 
the bones at a much later period of life. 

' 409. As the animal matter of the bones diminishes in 
old age, they become hard and brittle. In an aged per¬ 
son, a very slight slip or miss-step is sufficient to produce a 
fracture. Fortunately, the failure and decline of all the 
other powers compel this class of persons to move with so 

In what state do bones exist at first ? How are they converted into bone ? 
Which portion of the bones continues to increase and which to diminish to 
old age ? What proportion of the bones is animal matter in children ?—in 
adults?—in old age? What is the condition of the bones in children? 
To what injury are the bones most liable at this age ? How are infants made 
bow-legged ? At what age do the bones arrive to perfection ? What is the 
condition of the bones in old age ? To what injury are the bones of the aged 
liable ? 




198 


CLASS-BOOK OF PHYSIOLOGY. 


much care and caution, that the frailty of this part of the 
system is but seldom tested. 

410. The earthy and animal portions of the bones can 
be easily separated from each other. To obtain the ani¬ 
mal portion, we have only to soak the bone a few days in 
a diluted acid. When the earthy matter is then dissolved, 
the animal matter which is left becomes so soft and plia¬ 
ble, that a bone of sufficient length can easily be tied into 
a knot, as represented in Jig. 2, Pl. XYII. 

411. By exposing a bone to the action of a hot fire, the 
animal matter will be consumed, leaving it so brittle that 
it may be easily crumbled into fragments. 

412. The bones of nearly all the higher animals present 
a great variety of form and structure, according to the 
position they occupy. 

413. The principal bones of the extremities are long 
and cylindrical, and consist of a shaft and two extremities. 
The shaft of a long bone is dense and hard in structure, 
and hollow in the centre, forming a cylinder or a double 
arch—a form which, it is well known, receives the greatest 
amount of strength. The extremities of the long bones 
are broad and expanded, so as to present a large surface to 
articulate with adjoining bones, and their internal struc¬ 
ture is cellular and cancellous, so as to secure as much bulk 
as possible in proportion to the quantity of matter. The 
internal structure of the long bones may be seen by a sec¬ 
tion of the thigh-bone, Jig. 3, Pl. XYII. 

414. The different bones of the body are united to each 
other by articulations and joints. 

415. The different bones of the cranium and skull, which 
surround and protect the brain, are very firmly united by 

How can we separate the animal from the earthy portion of the bones 1 
How the earthy portion ? What is said of the bones of the higher animals ? 
What is the form of the principal bones of the extremities? Describe the 
shaft, and the extremities of a long bone. How are the different bones of the 
body united to each other? How are the different bones of the cranium 
united together ? 









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XVIII. 


o 

PLATE 


ORGANS OP MOTION.-THE BONES. 


Figure 1.- Posterior View of the Human Skeleton. — The Head. — a, The frontal-bone. 

A, b , The parietal bones, c, The left temporal-bone, d, The occipital-bone. 

The Trunk. —1, 1, 1, Spinous processes of the vertebrae, t, t, t, Transverse processes 
of the vertebrae. 2, 2, The ribs. 3, The os innominatum, showing its three parts, viz: a, 
the ileum; b , the ischium; c, the os pubis. 4, The sacrum. 5, The coccyx. 

The Superior Extremities. — 6, The scapula. 7, Acromion process of the scapula. 
8, The clavicle. 9, Head of the humerus placed in the glenoid cavity of the scapula. 10, 
Shaft of the humerus. 11, 12, Internal and external condyles of the humerus. 13, The 
olecranon process of the ulna, which articulates with the pulley-like surface at the lower 
end of the humerus, forming the elbow-joint. 14, Shaft of the ulna. 15, Shaft of the 
radius. 16, Lower extremity of the radius, which articulates with the bones of the carpus. 
17, Bones of the carpus. The first row consists of four bones, viz: a, the scaphoid-bone; 
A, the semi-lunar-bone; c, the cuneiform-bone; d, the pisiform-bone. The second row 
consists of four bones, viz: e, The trapezium. /, The trapezoid-bone, g, The os magnum. 
A, The unciform-bone.—18, 18, Bones of the metacarpus. 19, 19, 20, 20, 21, 21, First, sec¬ 
ond, and third ranges of finger bones. 

The Inferior Extremities.— 22, Head of the femur, placed in the acetabulum or 
cotyloid cavity of the haunch-bone. 23,24, Projections called trochanter major and minor, 
to which the muscles of the hip are attached. 25, Shaft of the femur. 26, 27, External 
and internal condyles of the femur. 28, Upper extremity of the tibia, which articulates 
with the femur. 29, Shaft of the tibia. 30, The internal malleolus, a projection of the 
tibia which forms the inner ankle. 31, The fibula. 32, External malleolus, a projection 
of the fibula which forms the outer ankle. 33, Bones of the tarsus. 34, Bones of the 
metatarsus. 35, Bones of the toes. The ligaments of the various joints are seen on the 
left side of this figure. 

Figure 2.- The Knee-joint. —j?, The knee-joint, with the patella removed, a , a, The 

condyles of the femur, covered with cartilage. A, A, The two semi-lunar cartilages, which 
form cup-shaped depressions for the reception of the condyles, c, The anterior crucial 
ligament which passes from the tibia to the femur. B , Section of the knee-joint, showing 
the reflections of the synovial membrane, a, The cancellous structure of the lower part 
of the femur. A, The tendon of the extensor muscle of the leg. c, The patella, rf, The 
ligaments which attach the patella to the head of the tibia, e, The cancellous structure 
of the head of the tibia. /, The anterior ligament, g, The posterior ligament. The synovial 
membrane may be traced along the under surface of the patella and its ligaments, and 
then over the head of the tibia, over the posterior ligaments, and then over the lower part 
of the femur. 

Figure 3.- J1 Section of the Hip joint. — a, The head of the femur. A, A, The capsulai 

ligament, embracing the cavity of the hip-bone and the head of the femur, and keeping 
both bones firmly together, c, A round ligament attached to the inside of the cavity and 
to the head of the femur. 

Figure 4.- The Bones of the foot , seen vpon the upper siLrface. —a, The os calcis, or 

heel-bone. A, The astragalus, which articulates with the lower end of the tibia, c, The 
cuboid-bone, d, The scaphoid-bone, e, c, e, Cuneiform bones. 





PL. XVIII 


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ANIMAL MOTION. 


203 


sutures (seams), which are formed by the interlocking of 
the ragged edges of one bone into corresponding notches 
in the adjoining one. These bones are thus so firmly 
united together in man at adult age, that it is difficult to 
separate them, except by breaking away some of the pro¬ 
jecting parts. 

416. The bones forming joints are firmly bound together 
by muscles and ligaments, and the end of each bone cov¬ 
ered over by a thin layer of cartilage, which has a smooth 
glassy surface. Each joint is inclosed by a sac or capsule 
of serous membrane, which secretes a peculiar fluid, called 
synovial fluid. The office of the synovial fluid is to keep 
the joints constantly moist and supple. 

417. After a severe injury to the joint, the synovial 
fluid is sometimes secreted in excess, causing “ dropsy of 
the joint.” 

418. The beautiful smoothness of the surfaces of the 
cartilages, and the manner in which the bones are bound 
together by ligaments and muscles, may be seen by ex¬ 
amining the knee-joint of any of our domestic animals. 
In fig. 2, Pl. XVIII., is a section of the knee-joint in man, 
showing the reflection of its synovial membrane. 

419. There are several kinds of joints in the body, the 
most important of which are the hinge-joint at the elbow 
and knee, and the ball-and-socket joint at the hip and 
shoulder. 

420. In the hip-joint, the socket is much deeper than 
at the shoulder—an arrangement evidently designed to 
give greater security against dislocation in a part on which 
the weight of the whole trunk must press in walking, run- 


How are the sutures formed? What is said of their firmness at adult age? 
How are the bones forming joints bound together ? How is the end of each 
bone covered? How is each joint inclosed? What is the office of the syno¬ 
vial fluid? How is this fluid sometimes affected by an injury? How may 
the structure of a joint be seen? How many kinds of joints are there? 
What is said of the hip-joint? What circumstance seems designed to pre¬ 
vent dislocation at the hip-joint ? 





204 


CLASS-BOOK OF PHYSIOLOGY. 


ning, leaping, &c. There is also a strong cord, fastened by 
one end to the top of the thigh-bone, and by the other to 
the socket in which it moves. 

J 5Cg21. The skeleton of man is formed by the union of 
about two hundred and fifty bones, and is divided into 
head, trunk, and extremities. 

422. The head includes the bones of the face and the 
cranium; the trunk includes all the bones immediately 
attached to the spine, except the head; the extremities 
embrace all the bones of the shoulders, arms, and legs, 
which are called upper and lower extremities in man, or 
the anterior and posterior extremities in quadrupeds. 

423. The face is formed by the union of fourteen bones, 
which serve for the lodgment and protection of the organs 
of sight, smell, and taste. 

424. The cranium or skull is a bony case, of an oval 
form, occupying the upper and back part of the head, and 
serving for the protection of the brain, which is lodged in 
its cavity. Its walls are made up of eight bones, which 
are firmly united to each other in such a manner that every 
part is admirably adapted to resist external force. 

425. The cranium is constructed on the principle of the 
arch, the bones at the base of the skull overlapping those 
above so firmly, that a separation is rarely, if ever, effected 
during life, and only with great difficulty after death. 

426. The spinal column or back-bone, as it is common±y 
called, consists in man of thirty-three different bones, called 
vertebrae. , which are divided as follows, in man: seven 
cervical vertebrae, (vertebrae of the neck,) twelve dorsal 
vertebrae, (vertebrae of the back,) five lumbar vertebrae, 
(vertebrae of the loins,) five sacral vertebrae, four coccygeal 


Of how many bones is the skeleton of man formed ? How is it divided? 
What bones are included in the head ?—the trunk ?—the extremities ? Of 
how many bones is the face formed? Describe the cranium. Its walls are 
made up of how many bones ? On what principle is the cranium constructed ? 
How is a separation of the bones prevented ? Of how many bones does the 
spinal column consist ? How are they divided ? 


ANIMAL MOTION. 


205 


vertebrae. All these vertebrae are separate at the time of 
| birth, but the five sacral vertebrae are soon after united 
into one piece—the sacrum—and the four coccygeal ver¬ 
tebrae are also united into one piece, the coccyx. 

- 4&7. The number of the cervical vertebrae is the same 

, in ajl the mammalia. Birds have a much larger number: 

the swan, which is remarkable for the gracefulness and 
j beauty of its neck, has twenty-three vertebrae, the crane 
, has seventeen, and the swallow thirteen. 

428. The number of the dorsal vertebrae is the same as 
,! the number of the ribs on each side. In man, there are 

twelve dorsal vertebrae, in the lion thirteen, and in the 
* elephant twenty. 

429. The vertebrae are perforated by an aperture, so 
l that when they are all united, they form a continuous tube 
: or canal for the lodgment of the spinal cord. 

480. By the division of the spinal column into so large 
| a number of separate bones, very great freedom of motion 
1 is allowed, with only a slight bend at any particular point. 

481. Each vertebras consists of a body, which is situated 
J in front of the spinal canal in man, and below it in quad¬ 
rupeds ; and of seven processes or projections, which serve 
to form the spinal canal, and unite the vertebrae to each 
other by affording attachments for the muscles. 

482. In man and the other mammalia, the two surfaces 
I of the body of the vertebrae are nearly flat, and are sepa- 
(i rated from each other by a disc of fibro-cartilage. ? 

433. In reptiles and fishes, a different plan is adopted. 

‘ ! In serpents, one surface of each vertebra is concave and 
fti the other convex, and thus the convex surface of each 

I What change takes place with the five sacral vertebrae ? What is said of 
the number of the cervical vertebrae in the mammalia ?—in birds ? How many- 
cervical vertebrae has the crane and the swallow? What do the vertebrae 
form when united together? What is gained by the division of the spinal 
column into so many separate pieces? Of what does each vertebrae consist? 
What is the form of the two surfaces of the body of the vertebrae ? What is 
the form in fishes and reptiles ? What kind of a joint do they form ? 



206 


CLASS-BOOK OF PHYSIOLOGY. 


vertebra fits into the concave surface of the next, in such 
a manner that the whole spine becomes a series of ball- 
and-socket joints—an arrangement which is remarkably 
adapted to the peculiar movements of those animals. 

434. In fishes, both surfaces are concave, and between 
each vertebra there is interposed a bag, containing fluid, 
and having two convex surfaces, over which those of the 
vertebrae can freely play. Very great freedom of motion 
is thus acquired, though the strength is proportionably 
diminished. But great strength is not required by ani¬ 
mals whose bodies are supported by a medium which is 
nearly of the same density with themselves. 

435. The extreme flexibility of fishes enables them to 
propel their bodies by the movements of the tail and 
hinder parts from side to side, their fins being used prin¬ 
cipally for influencing their direction. 

436. Man is the only animal whose spine seems adapted 
to the erect attitude. Its form has some resemblance to 
the letter S, being a double curve, and it thus forms a 
kind of spring that is admirably adapted to diminish the 
shock produced by a sudden jar, as in the act of jumping 
upon the feet from a height. The bodies of the vertebrae 
are also broader, in proportion to their size, than in other 
animals, while the spinous processes, which form the ridge 
along the back, are considerably shorter In quadrupeds 
which maintain a horizontal position of the spinal column, 
the spinal processes are very long, for the attachments of 
muscles to support the head. In figs. 9 and 10, Pl. XIX., ■ 
may be seen a comparative view of the vertebras in the 
lion and ox. 

437. The ribs, which are twelve on each side in man, 
are attached by one extremity to the transverse processed 

How are the two surfaces separated in fishes? How do fishes propel therri 
bodies ? For what purpose are fins used ? What attitude is peculiar to man ? 
What is the form of the spine in man ? What advantage is obtained by this 
form ? How do the vertebrae in man differ from those of all other animals ? 
What is said of the spinal processes in quadrupeds ? How many ribs are 
there in man ? What are the attachments of the ribs ? 





































































































PIATE XIX 


THE EXTREMITIES. 


Fioure 1.- Anterior Extremity of Man. —a, Scapula, or shoulder blado. Z>, Tho 

humerus, or principal bone of the arm. c, The radius. d, The uina. a, The carpus, or 
wrist. /, The metacarpus, or palm, g. The phalanges, or fingers. 

In figures 2,3,4,5, 6, 7, and 8, the corresponding bones are indicated by the same letters 
as in figure 1. 

Figure 2.- Anterior Extremity of the Deer. 

Figure 3.- Anterior Extremity of the Lion. 

Figure 4.- Anterior Extremity of the Whale. 

Figure 5.- Anterior Extremity of the Bat. 

Figure 6. - Anterior Extremity of the Bird. 

Figure 7.- Anterior Extremity of the Sloth. 

Figure 8.- Anterior Extremity of the Monkey. 

Figure 9. - Skeleton of the Lion—a, The skull, b, The cervical vertetrse. c, The 

dorsal vertebrae, d, The lumbar vertebrae, e , The sacrum. /, The caudal vertebrae, which 
compose the tail, g, The ribs, h, The scapula, i, The humerus, j, The fore-arm.—In 
this part, corresponding to the fore-arm of man, the two bones are united into a single 
one. k, Bones of the wrist, or carpus. /, Bones of the metacarpus, or hand, m, Tho 
phalanges, n, The femur, or thigh-bone, united to the bones of the pelvis, o, The patella, 
or knee-pan. p, The tibia; the two bones of the leg being united into one. q, Bones of 
the tarsus, or ankle, r. Bones of the foot and toes.—In the lion, the bones of the arm are 
stout and long, and the fingers short and compact, collectively combining freedom of motion 
and strength, and admirably adapting this class of animals to the sudden springs with 
which they pounce upon their prey. 

Figure 10.- Head and Shoulders of an Ox. — a, The skull, b , The cervical verlebr®. 

c, The dorsal vetebrae, which are very long, for the attachment of the muscles which sup¬ 
port the neck anil head, d, The scapula, or shoulder-blade. 






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ANIMAL MOTION. 


211 


of the dorsal vertebras, and by the other to cartilages which 
are continuations of the ribs. The cartilages of the first 
seven, or true ribs, ( aa,ftg . 1, Pl. XVII.,) are united to the 
sternum or breast-bone; the cartilages of the five lower 
ribs ( bb , fig. 1, Pl. XVII.) are not directly connected with 
the sternum, and are hence called false ribs. 

438. The sternum , or breast-bone, {fig. 1, Pl. XVII.) is 
flat in man, but in those animals which have need of great 
strength in the upper limbs it is increased in breadth, and 
furnished with a projecting keel or ridge for the attach¬ 
ment of powerful muscles. In the turtle tribe, it is so far 
extended as to afford a complete protection to the under 
side of the animal. 

439. The extremities, which have been regarded as 
appendages to the trunk, are four in number in all the 
vertebrated animals, and are constructed on the same 
general plan, though they are widely different in general 
appearance. The fin of a fish, the wing of a bird, the leg 
of a lion or a deer, and the arm of man, are evidently 
adapted to very different uses, and are apparently destitute 
of any very striking resemblance to each other; yet, when 
those same limbs are stripped of the skin and muscles, 
they will be found to possess the same essential parts, 
slightly modified, according to their several uses. 

440. One of the superior extremities of man, and one 
of the anterior extremities of a deer, a lion, a whale, a bat, 
and a bird, are represented by the same letters in figs. 1, 
2, 3, 4, 5, and 6, Pl. XIX. 

441. The scapula , or shoulder-blade, is a large flat bone, 
attached to the back part of the trunk by muscles. In 

. How many of the cartilages are attached directly to the breast-bone? 
What are the five lower ribs called ? What is the form of the breast-bone in 
man ?—j n those animals which have need of great strength in the uppei 
limbs? What is said of it in the turtle? How many extremities are there 
in all the vertebrated animals? What is said of their construction? What 
illustrations are given ? Describe the scapula or shoulder-blade. How is it 
attached to the trunk? What advantages are derived from this kind of 
attachment ? 


212 


CLASS-BOOK OF PHYSIOLOGY. 


animals which walk on all-fours, this kind of attachment 
secures much greater elasticity of movement, and also 
diminishes the force of the shock in the acts of leaping or 
running. In man, it gives greater freedom of motion to 
the arm. 

442. The clavicle , or collar-bone, is attached at one ex¬ 
tremity to the shoulder-blade, and at the other to the 
sternum or breast-bone. It acts as a brace to separate the 
shoulders, and it is accordingly strongest in those animals, 
the action of whose superior extremities tend to draw them 
together; while it is comparatively weak, or altogether 
deficient, in those animals, the action of whose limbs nat¬ 
urally tends to keep them asunder. Thus, in birds, there 
is not only a strong clavicle, but a second bone also, tend¬ 
ing to keep the shoulders apart. In the lion, deer, &c., it 
is entirely wanting. 

443. The arm is supported by a single long and cylin¬ 
drical bone, c, the humerus. In the fore-arm, there are 
two long bones, the radius and ulna ( d , e), which lie par¬ 
allel to each other. The radius is on the outer or thumb 
side of the fore-arm, and the ulna on the inside. The 
radius and ulna are connected with one another by liga¬ 
ments at their extremities, and by a strong fibrous mem¬ 
brane, that passes between their adjacent edges along their 
entire length. Those bones rotate freely on each other, in 
such a manner that either the palm or back of the hand 
may be turned. In most quadrupeds, the radius and ulna 
are so firmly united together as to be incapable of rotation. 

444. The hand is anatomically divided into three por¬ 
tions—the carpus , metacarpus , and phalanges. The carpus, 

What are the attachments of the clavicle ? What is the use of this bone ? 
[n what animals is it strongest? In what animals weakest? How is it in 
birds ?—in the lion, deer, See. ? How is the arm supported ? How many bones 
are there in the fore-arm, and what are they called? On which side is the 
radius?—the ulna? How are the radius and ulna connected to each other? 
How do these bones rotate on each other ? In what condition are the radius 
and ulna in most quadrupeds? How is the hand anatomically divided? 
f^cribe the carpus—the metacarpus—the phalanges. 



ANIMAL MOTION. 


218 


which is nearest the wrist-joint, is composed of eight small 
bones, "which are firmly united to each other by ligaments 
—the metacarpus, which consists of five long cylindrical 
bones, resembling the bones of the fingers so much, that 
in the skeleton they might be easily mistaken for their 
joints. The fingers are formed by a-series of small bones, 
called phalanges, of which there are only two in the 
thumb, and three in each of the fingers. 

445. As the foot and ankle, which correspond to the 
wrist and hand in man, are designed for solidity in quad¬ 
rupeds, we find in different parts that there is only one 
solid piece for two, three, or more 
bones in corresponding parts in 
man, though those solid pieces are 
found originally to have been sev¬ 
eral distinct bones that have after¬ 
wards united. Thus, in the rumi¬ 
nating animals, as the deer {fig. 59), 
the number of phalanges is reduced 
to two, and in the horse {fig. 60), 
there is but one, which is enveloped 
by the hoof. 



Fig. 59 . 


Fig. 60 . 


446. The structure of the lower 
extremities has a very great analogy 
to that of the upper, the principal 
differences being such as are necessary to make the lower 
extremities more solid, and better adapted to serve as 
organs of locomotion, instead of organs of prehension. 

447. The lower extremities are connected with the spine 
by a bony case or basin, called the pelvis. The thigh, 


How many phalanges are there in the thumb ?—in the fingers ? How are 
the foot and ankle in quadrupeds made more solid than the wrist and hand 
in man ? Are these parts found solid originally ? How many phalanges are 
there in the deer?—in the horse? How do the upper and lower extremities 
differ from each other? How are the lower extremities connected with the 
spine? How is the thigh supported ? 



214 


CLASS-BOOK OF PHYSIOLOGY. 


like the arm, is supported by a single long cylindrical bone, 
called the femur , which is bent at the upper extremity at 
an angle, and its rounded head separated from the main 
bone by a narrow portion, called its neck. The lower end 
of the thigh-bone spreads into long condyles, on which 
the large bone of the leg moves backward and forward. 

448. The leg has two bones, but they do not possess the 
power of rotating on each other like the fore-arm. The 
main bone, or tibia, is much larger than the fibula , which 
is a long slender bone, running parallel with the tibia, 
and apparently serving no other purpose than to give 
attachment to the muscles. The upper end of the tibia is 
broad, and has two shallow depressions, in which the con¬ 
dyles of the femur or thigh-bone are received. 

449. In front of the knee-joint is a small bone, called 
the patella, which serves the double purpose of protecting 
the joint and changing the direction of the tendon which 
comes down from the thigh. 

450. The foot is composed, like the hand, of three dis¬ 
tinct portions—the tarsus , the metatarsus , and the phalanges 
or toes. There are seven bones in the tarsus, all of which 
are larger than those of the carpus. The metatarsus is 
composed of five long bones in man. The toes, like the 
fingers, have three phalanges, each, except the great-toe, 
which has only two. The tarsus and metatarsus form a 
kind of arch on the inside of the foot, which serves to 
lodge and protect the vessels and nerves that descend from 
the legs to the toes. This arch also serves to deaden the 
shock that would be experienced every time the foot was 
put to the ground; for by the elasticity of the ligaments 
which bind these bones together, a kind of spring is 

What is the form of the upper extremity ?—of the lower extremity ? How 
many bones form the leg ? What is their comparative size ? Describe the 
tibia. What bone in front of the knee-joint ? What is its use 1 Of how 
many portions is the foot composed, and what are they called ? How many 
bones in the tarsus?—the metatarsus? How many phalanges are there in the 
toes? What do the tarsus and metatarsus form? What advantages are 
derived from this form of the foot ? 




























































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PLATE XX 


ORGANS OF MOTION.-THE BONES. 


Figure 1.- Skeleton of the Camel.— The black ground in this and tho two following 

figures shows the outline of the form when clothed with flesh, a , The 6 kull. b , The cer¬ 
vical vertebra;, c, The dorsal vertebras.—'The spinous processes of these vertebrae are 
much longer and larger than those of man, for the purpose of giving attachment to the 
strong muscles and ligaments by which the heavy neck and head are supported, d , The 
lumbar vertebra;, e, The sacrum. /, The caudal vertebrae, which compose the tail, g, 
The ribs. A, The scapula, i, The humerus, y, The fore-arm.—In this part, corresponding 
to the fore-arm of man, the two bones are united into a single one. k , Bones of the wrist 
or carpus. Z, Bones of the metacarpus or hand, to, The phalanges, n, The femur, or 
thigh-bone, united to the bones of the pelvis. 0 , The patella, or knee-pan. p, The tibia; 
the two bones of the leg being united into one. < 7 , Bones of the tarsus or ankle, r, Bones 
of the foot and toes.—In animals which do not possess fingers, the bones of the fore-arm, 
wrist, and hand are always few in number. Thus, in the camel, and in all herbivorous 
quadrupeds, the fore-arm has only one bone; the wrist, about four; the hand, only one, 
with sometimes the rudiment of another; while some species have two toes, and others 
only a single one. 

Figure 2.- Skeleton of the Vulture. —rc, Cervical vertebrae, fifteen in number. A, 

Dorsal and lumbar vertebrae, vs , The sacrum, v < 7 , Vertebrae of the tail, st, The breast¬ 
bone, or sternum, cl , The clavicle. A, The humerus. 0 , The two bones of the fore-arm. 
ca , Bones of the wrist, imperfectly developed, pA, Bones of the hand and fingers. /, The 
thigh-bone. Z, The two bones of the leg. ta, The shank or ankle bones. 

Figure 3.- Skeleton of Turtle.—a, Cervical vertebrae. A, Scapula, c, Clavicle. <Z, 

Coraooid-bone. e, Dorsal vertebrae. /, Ribs incorporated with the dermal plates which 
form the shell, g , Marginal plates. A, Pubic bones, t, Femur. A, Tibia. Z, Fibula. 

Figure 4.- Skeleton of the Perch. —a, A, First and second dorsal fins, c, The caudal 

or tail-fin. <Z, The anal-fin. 0 , One of the ventral fins, which correspond to the legs. /, 
One of tho pectoral fins, which are analogous to the ar»s. The spinous processes of the 
vertebrae are long, and are connected with another set of bones, by which they are con¬ 
tinued upward, so as to form the frame-work of the fins which arise from the back. The 
whole number of vertebrae is forty-two, of which twenty-one are dorsal and twenty-one 
caudal or coccygeal. The number of pairs of ribs is the same as that of the dorsal vertebra;. 






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ANIMAL MOTION. 


219 


formed, which yields for a moment to the shock, and then 
recovers itself. 

451. In animals which walk on all-fours, the difference 
of direction in which the bones of the legs are connected 
with the spine, prevents a jar from extending to the body. 
In those animals which obtain their food by sudden and 
extensive leaps—such as the cat, tiger, and lion—there is 
an arrangement of the bones admirably adapted to dimin¬ 
ish the shock produced by a sudden descent of the body 
upon the ground. 


THE MUSCLES. 

452. The muscles are the moving power by which the 
parts of the skeleton are set in motion. 

453. Each muscle, if examined carefully, is found to be 
made of a number of bundles of fibres, and each fibre is 
formed of numerous smaller fibres or fibrils. The primi¬ 
tive fibrils are only about T o,vo o^h of an inch in diameter. 
Each fibre, which extends from one end of the muscle to 
the other, is supplied with one or more loops of nervous 
filaments. Through the influence of the nervous system, 
the muscular tissue is capable of being excited to sudden 
and forcible contraction. In contracting, the two ends of 
a muscle approach each other, and swell out in the middle 
to a corresponding degree. Thus, the whole muscle, when 
shortened by the drawing together of its two ends, is 
greatly enlarged in diameter, especially towards the middle. 

454. The energy of muscular contraction depends, in a 
great degree, upon the power of the stimulus which is 
transmitted to the muscles from the brain. 


In animals which walk on all-fours, how is a jar prevented from extending 
to the body? How are the parts of the skeleton set in motion ? Of what is 
each muscle made up ? What is the size of the primitive fibrils ? With what 
is each fibre supplied? How is the muscular tissue excited to contraction? 
What change takes place in a muscle when it contracts ? When is the muscle 
enlarged most in diameter ? Upon what does the energy of the muscular 
contraction depend ? 


220 


CLASS-BOOK OF PHYSIOLOGY. 


455. This is frequently observed in instances of great 
nervous excitement, as when a person is under the influ¬ 
ence of violent passion or insanity. A delicate female is 
thus often a match for three or four strong men, and can 
even break * cords and bands that would hold the most 
powerful man. 

456. In the production of animal motion, the bones not 
only serve as points of attachment for the muscles, but 
they constitute a series of levers for the application of 
muscular force. 

457. Most of the muscles act on the bones at great 
mechanical disadvantage, though it is a law in mechanics 
that what is lost in power is gained in time. Thus, in 
fig. 76, the muscle (a) which arises from the top of the 



Fig. 61 . 


shoulder, and is inserted at e, a short distance from the 
elbow, acts at a great mechanical loss of power in raising 
the fore-arm, but its contraction to a very slight extent 
will raise the hand through a considerable space. Thus, 
since the muscle is inserted about one-sixth of the distance 
from the elbow to the wrist, it will require a force of con¬ 
traction in the muscle equal to six pounds to raise one 
pound at the wrist, while its contraction of one inch will 


In what cases of great nervous excitement is this frequently observed 1 
What example is given ? What other purpose do the bones serve besides 
affording attachment for the muscles'? How do most of the muscles act on 
the bones ? What law of mechanics in regard to this? Explain Figure 65 
What force in the muscle will be required to raise one pound at the wrist? 






















Kart( onn 


K~el?o|o. LitK? 










































































PLATE XXI. 


ORGANS OF MOTION.-THE MUSCLES 


LATERAL VIEW OF THE PRINCIPAL MUSCLES OF THE HUMAN BODY. 

Muscles of the Head, and Meek .—1, The occipitofrontalis muscle, which elevates the 
eyebrows, and wrinkles the forehead, expressing astonishment or attention. 2, The orbic¬ 
ularis palpebrarum, which closes the eyelids. 3, Triangularis nasi, which compresses the 
nostrils. 4, The levator labii superioris, which raises the upper lip and expands the nos¬ 
trils, expressing disdain. 5, Zygomaticus major. 6, Zygomaticus minor: These muscles 
raise the upper lip and draw it outward. 7, Orbicularis oris.—Only half of this muscle 
is seen on the plate. It extends completely around the mouth, which its action is to close. 
It also assists the lips in whistling, blowing and sucking. 8, The buccinator, or trumpet¬ 
er’s muscle.—It elongates the mouth transversely, and is greatly used in blowing wind- 
instruments. -9, Depressor labii inferiors, which draws down the under lip, expressing 
chagrin, disgust. 10, Depressor anguli oris, which depresses the angle of the lips. 11, 
The masseter.—This powerful muscle is the essential agent in mastication. It raises the 
lower-jaw, and brings its teeth strongly against those of the upper-jaw. 12, Omo-hyoideus, 
extending from the edge of the scapula to the hyoid-bone, which it depresses. 13, Sterno- 
hyoideus, a depressor of the larynx. 14, The digastricus, an elevator of the larynx and a 
depressor of the lower jaw. 15, The Sterno-cleido-mastoideus, extending from the tem¬ 
poral-bone to the sternum and clavicle.—When one of these contracts, it draws the head 
to its own side; when both contract, the head is carried forward. 16, The upper portion 
of the trapezius.—( See Plate XXII.) 17, 18, Scalenus posticus and anticus, which ele¬ 
vate the ribs and assist in respiration. 

Muscles of the Trunk. —19, The pectoralis major, a large muscle, attached to the clavi¬ 
cle, sternum and ribs, and to the humerus. It draws forward the shoulder, and also ele¬ 
vates the ribs, acting as a muscle of inspiration. 20, The serratus magnus, a powerful 
muscle, lying beneath the pectoral muscle.—It is divided into slips or digitations, which 
extend from the ribs to the scapula. It is a muscle of inspiration, the contraction of its 
slips tending to separate the ribs and thus dilate the chest. 21, 21, &c. External inter 
costal muscles, which elevate the ribs. 22, The transversalis abdominis. This muscle 
draws the front of the abdomen inward, thereby pushing up its contents against the dia. 
phragm, in the act of expiration. 23, Rectus abdominis, which draws the chest forward 
toward the pelvis, and assists in straightening the trunk when it has been thrown backward. 

Muscles of the Superior Extremities. —24, The deltoid muscle. This thick and powerful 
muscle is attached to the scapula and to the humerus. Ordinarily it elevates the arm ; 
but when the body is raised by the arms, as in climbing, it draws up the trunk. 25, The 
biceps brachialis.—This is the large muscle whose projection is felt in front of the arm. 
It is a flexor of the fore-arm. 26, 26,26, Portions of the triceps brachialis.— (See Pl. XXII). 
27, The pronator teres.—This muscle, being attached to the radius, and having its fixed 
insertion on the humerus, rolls the radius inward, and thus turns the palm of the hand 
downward. 28, The supinator longus.—This muscle acts as an antagonist to the last, and 



224 


CLASS-BOOK OF PHYSIOLOGY. 


turns the hand upward. 29, The flexor carpi radialis. 30, The palmaris longus. 31 
Flexor carpi ulnaris.—These three muscles are flexors of the wrist upon the fore-arm. 
Their white and slender tendons are attached to the carpal and metacarpal bones. 32, 
Tendons of the flexor sublimis digitorum, which bend the second range of the finger-bones 
upon the first. 33, Extensor carpi radialis longior.—This muscle extends the wrist upon 
the fore-arm. 34, Extensor communis digitorum.—( See Pl. XXII.) 35, Lower portion 
of the abductor pollicis longus. 3G, Lower portion of the extensor pollicis brevis.—These 
two muscles draw the thumb outward, and bend it on the carpus. 37, Extensor carpi 
ulnaris.—( See Pl. XXII.) 

Muscles of the Inferior Extremities.— 38, The rectus intemus.—This cjuscle is a flexor 
of the leg. 39, The sartorius or tailor’s muscle, the longest muscle in the body.—By its 
action the legs are bent inward, so as to cross each other. 40, The rectus femoris. 41, 
The vastus intemus. 42, The vastus externus.—These three muscles extend the leg upon 
the thigh. 43, Portion of the adductor magnus.—This muscle draws backward the thigh 
at the hip. 44, A portion of the gluteus maximus.—( See Pl. XXII.) 45, The gluteus 
medius. 4G, A tendinous expansion called the fascia-lata, forming part of the femoral 
aponeurosis. 47, The tendon of the vastus femoris, which contains the patella. 48, The 
triceps surae, or extensor of the foot, composed of three large fasciculi.— (See Pl. XXII.) 
49, The peroneus longus; its tendon passes behind and beneath the outer ankle, in a pul¬ 
ley-like groove, and is inserted into the first metatarsal-bone. By its contraction, this 
muscle extends and rotates the foot. 50, The tibialis anticus.—This muscle is attached 
by its tendon to a bone of the instep, and bends the foot upward. 51, The extensor digi¬ 
torum communis.—Its four tendons are seen proceeding under the annular ligament of 
the tarsus, and diverging to the four smaller toes. This muscle extends the joints of the 
toe3, and bends the foot upon the leg. 52, Annular ligament of the tarsus. 53, Adductor 
pollicis pedis.—(Sec Pl. XXII.) 



ANIMAL MOTION. 


225 


move the wrist through six inches 
of space. In the same manner the 
muscle m {fig. 62), which lies on the m 
back of the arm, and contracts in 
the direction of the letter n, acts 
with a similar disadvantage in re¬ 
gard to power, though it has a Fig. 62 . 

corresponding advantage in point of time. 

458. Under ordinary circumstances, the energy of mus¬ 
cular action depends on the condition of the muscles 
themselves. Those muscles which are firm, plump, and 
high-colored, act with greater force than those which are 
pale and flabby. In the sedentary and inactive, the mus¬ 
cles are smaller in size and less vigorous than in those 
whose habits are more active. Within certain limits, the 
muscles increase, both in size and power, by use. In the 
smith, who makes constant use of his arms, the muscles 
are proverbially large and powerful; in the pedestrian, 
the muscles of the legs become developed. 

459. The free exercise of the muscles not only increases 
the general strength, but greatly improves the vigor and 
health of all the physical powers. 

460. The energy of muscular contraction appears to be 
greater in insects, in proportion to their size, than in any 
other animals. Thus, a flea will leap sixty times its own 
length, and move as many times its own weight. The 
same muscular power, in a man of six feet, would enable 
him to leap a distance of over three hundred feet, and to 

If this muscle contracts one inch, through what space will it move the wrist? 
Under ordinary circumstances, upon what does the energy of muscular con¬ 
traction depend ? What kind of muscles act with greatest energy ? What 
is said of the muscles in the sedentary and inactive ? How are the muscles 
affected by use ? What is said of the arms of the smith, and the legs of the 
pedestrian ? What is said of the influence of exercise on the muscles, and on 
the health of all the powers ? In what animals is the energy of muscular 
contraction greatest in proportion to size ?’ How far will a flea leap ? How 
far would the same muscular power in man enable him to leap ? How much 
would it enable him to lift ? 



226 


CLASS-BOOK OF PHYSIOLOGY. 


lift a weight of over ten thousand pounds. A species of 
beetle can support a weight equal to at least five hundred 
times that of its own body; and another, by the power of 
its jaws, has been known to gnaw a hole of an inch in 
diameter in the side of an iron canister in which it had 
been confined. The rapidity of the movements in insects is 
also so great, that the vibrations of the wings in some species 
have been calculated at several hundred, and, in some of 
the smaller insects, at several thousand in a second of time. 

461. The various kinds of progression in different ani¬ 
mals are called swimming , crawling , flying , walking , running , 
jumping, &c. 

462. In fishes, the body is propelled through the water 
by the tail, on the same principle as a boat in impelled by 
sculling. The tail being vertical, in most cases its stroke is 
horizontal, and the body is propelled forward by the resist¬ 
ance of the water to its broad expansion, as it strikes from 



side to side, by the alternate contraction of the muscles 
which extend from the long process of the vertebrae to 
the tail. In the whale, the tail {fig. 63) is expanded hori- 

What is said of some species of beetle? What is said of the movements 
of insects? What are the various kinds of progression in animals called? 
How is the body in fishes propelled through the water? How is the stroke 
made against the water in most cases ? What propels the fish ? How is the 
tail expanded in the whale, and how is its stroke made ? What is said of the 
structure of the tail ?—of the power of the whale ? 





ANIMAL MOTION. 


227 


zontally, so that its stroke is vertical. The texture of the 
tail is such, that it is insensible to pain, and it is so tough 
that it is rarely torn or injured. The whale is therefore 
capable of inflicting a tremendous blow without any pain 
to itself, and of cutting a strong boat asunder, or of driv 
ing it with the swiftness of an arrow to the depth of many 
fathoms. 

463. The fins of fishes are used principally to give 
direction to the body as it is propelled through the water. 

464. In serpents, progression is effected by undulations 
of the spine, or by bringing the two extremities of the 
body near together, and then,- the tail being fixed, the 
head is projected forward the length of the body: again 
the tail is brought forward, and the same process repeated. 
Sometimes, instead of this alternate contracting, the whole 
body is brought into a spiral coil, and by the contraction 
of all the muscles on one side, and then by a sudden con¬ 
traction of the muscles of the opposite side, the whole 
body is propelled, as by the unwinding of a powerful 
spring, with an impulse which raises it to some height 
from the ground. 

^ 465. Flying has some resemblance to swimming, both 
being executed in a fluid medium, which, to a certain ex¬ 
tent, buoys up the body and offers resistance to its progress. 
Water, however, affords more support to the body and a 
greater. resistance to the propelling organs. Birds are 
especially adapted to flying by their formation. Their 
bones excel those of all other animals in combining strength 
and lightness. All the long bones are hollow cylinders 
filled with air. The breast-bone, which resembles in form 
the keel of a ship, presents a very large surface for the 
attachment of the muscles, and it is also connected very 

For what are the fins of fishes principally used? How is progression 
effected in serpents? What other mode of progression is there in some ser¬ 
pents? What does flying resemble ? How are birds adapted to flying? In 
what respect do the bones of birds excel all other animals ? What are the 
long bones ? What does the breast-bone resemble ? 


228 


CLASS-BOOK OF PHYSIOLOGY. 


firmly by the ribs to the vertebrae of the back. The whole 
bony apparatus of the body is thus very strongly knit 
together, and yet the entire skeleton is exceedingly light— 
the body being suspended in the air by the resistance it 
affords to the wings. The muscles which are attached to 
the breast-bone are much larger than in other animals; 
while the muscles on the back, that raise the wings, are 
correspondingly smaller. The greatest power of the wings 
is consequently in the downward direction. In the effort 
to fly, the wings are expanded, brought down with con¬ 
siderable force, and then brought up to the body, being 
raised again in such a form as to offer the least possible 
resistance to the air. 

466. In many birds the rapidity of flight is very great, 
much greater than by any other mode of progression. 
The Eider-duck is said to fly ninety miles an hour, and 
some species of hawk one hundred and fifty. 

467. Walking is produced by the alternate contraction 
and extension of the limbs. In man, one foot is placed in 
front upon the ground while the other is extended or car¬ 
ried backward, and its length increased, carrying forward 
the whole body. In quadrupeds, two feet are placed on 
the ground at once. 

468. In running, the body momentarily quits its sup¬ 
port on the ground at intervals, the foot in advance not 
being planted on the ground at the time, the hinder one 
quits it. In this action, the ostrich probably surpasses all 
other animals, as it is said to outstrip the swiftest grey¬ 
hound at its greatest speed. 

469. In trotting, the fore-foot of one side and the hind- 

What is gained by this peculiar form ? How is the bony apparatus united 
together ? What is said of the skeleton ? How is the body suspended in the 

air ? What is said of the muscles which are attached to the breast-bone ?_to 

the back? In what direction is the greatest power of the wings? Describe 
.he movement of the wings in the effort to fly ? What is said of the rapidity 
of flight in birds ? What examples ? How is walking produced ? How is 
it produced in man?—in quadrupeds? Describe running. What animal 
surpasses all others in running? Describe trotting. 







# * 

PLATE XXII. 


ORGANS OF MOTION.-THE MUSCLES. 


POSTERIOR VIEW OF THE MUSCLES. 

The right side of the figure displays the outer or superficial layer of muscltw. On the 
left side, they are represented clothed with their fascise or aponeuroses, which form a 
tendinous membrane. 

Muscles of the Head and JVcck. —1, The occipitalis.—This muscle draws the scalp back¬ 
ward and downward, giving the expressions of joy or surprise. 2, Muscles of the ear. 
3, The masseter. 4, The sterno-cleido-mastoideus. 5, The splenius.—When the two 
splenii act together, they draw the head backward, elevating the chin; when one acts, it 
bends the head and neck to one sid-e. 

Jifuscles of the Trunk. —6, The trapezius.—This muscle is attached to the spinous pro¬ 
cesses of the dorsal vertebrae and to the scapula. It carries the shoulder backward. 7» 
The latissimus dorsi.— a, a , Its tendinous or aponeurotic portion.—This broad muscle draws 
down the arm, or, if the arm be fixed, it draws the trunk towards the shoulder. 8, Part 
of the obliquus externus.—This muscle compresses and raises up the contents of the 
abdomen. 

4* 

Muscles of the Superior Extremities. —9, Posterior portion of the deltoid muscle. 10, 
The infra-spinatus.—This muscle turns the shoulder outward, and assists in keeping the 
head of the humerus in its socket. 11, 11, 11, The three portions of the triceps extensor 
cubiti.—This muscle is fixed by its tendon to the olecranon process of the ulna, and by its 
contraction it extends the fore-arm. 12, The extensor communis digitorum.—Its four 
tendons pass under the annular ligament, and go to the four fingers ; so that it becomes 
an extensor of the whole hand, as well as of each of the phalanges. 13, The extensor 
proprius of the little-finger.—By means of this slender muscle, the little-finger can be sep¬ 
arately extended. 14, The extensor carpi ulnaris.—This muscle extends the hand on the 
wrist. 15, Flexor carpi ulnaris. 16, Tendon of the long extensor of the thumb. /, An 
nular ligament of the carpus. 

Muscles of the Inferior Extremities. —17, The gluteus maximus.—This large, thick 
muscle is of greater volume than any other in the body, and is the principal agent in pre¬ 
serving its equilibrium. It extends from the iliac bones to the femur, and acts as an ex¬ 
tensor of the thigh. 18, The biceps femoris.—This strong muscle, extending from the 
pelvis to the tibia, bends the leg, and also extends the pelvis upon the leg, keeping it 
erect. 19, The semi-tendinosus.—This muscle bends the leg upon the thigh, turns the 
point of the foot downward and inward, and keeps the pelvis erect when standing. 20, 
The vastus externus. 21, 21, The triceps surae, consisting of three portions—the gastrocne- 
mii, a, b , and the soleus, c; it terminates in the strong tendon of Achilles, d. It forms the 
extensor muscle of the foot. 


































































* 








t 



























\ 


































. 


























ANIMAL MOTION. 


233 



foot of the other one are raised and carried forward to¬ 
gether; and when these are set down, the other fore and 
hind foot are raised and advanced. 

470. In leaping, the 
body is projected into 
the air by the sudden 
extension of the joints, 
especially those of the 
hinder parts of the body 
which have been previ¬ 
ously bent, and having 
traversed a greater or 
less distance, the body 
comes again to the 
ground. The hare, rab¬ 
bit, squirrel, kangaroo, 

&c., are especially adap¬ 
ted to this kind of pro- 

gression by the length 64 .-kako.ioo.. 

of the posterior extrem¬ 
ities, which are nearly double that of the anterior, as may 
bo seen in fig. 64. 


Describe leaping. 



234 


CLASS-BOOK OF PHYSIOLOGY. 


CHAPTER XIV. 

THE YOICE. 

471. The voice in animal and in man consists essen¬ 
tially in the production of sounds expressive of ideas, 
feelings, passions, and desires. 

472. Insects and all water-breathing animals may be 
said to be mute, since they have no voice. Insects, how¬ 
ever, possess the power of producing sounds by certain 
movements which to some extent are characteristics of the 
different species. The shrill chirp of the cricket is pro¬ 
duced by rubbing the wing-cases against each other. The 
harsh shriek of the grasshopper is caused by friction of 
the legs against the wings. The shrill trumpet sound of 
the mosquito and the busy hum of bees and flies are pro¬ 
duced by the rapid motion of the wings while flying. 
Other sounds are caused by the jaws in the act of masti¬ 
cating, as the remarkable “death-watch” so called.* 

473. In the air-breathing vertebrata, the production of 
sounds depends upon the passage of air through a certain 


In what does the voice consist? What animals may be said to be mute? 
Why may they be said to be mute ? How do insects produce sounds ? How 
is the chirp of the cricket produced ? How is the sound of a grasshopper 
caused?—the mosquito?—bees and flies? How are other sounds caused? 
How is sound produced in air-breathing vertebrata ? 

* “-^-A wood-worm, 

That lies in old wood, like a hare in her form! 

With teeth or with claws, it will bite or will scratch, 

And chamber-maids christen this worm a death-watch ; 
Because, like a watch, it always cries click! 

Then woe be to those in the house who are sick! 

For sure as a gun they will give up the ghost, 

If the maggot cries click when it scratches the post: 

But a kettle of scalding hot water ejected, 

Infallibly cures the timber affected: 

The omen is broken, the danger is over, 

The maggot will die, and the sick will recover.” 




THE VOICE. 


235 


portion of the respiratory tube. In reptiles, it is at the 
point where the trachea or windpipe opens into the pharynx 
that the vibratory apparatus is situated. The sounds pro¬ 
duced by this class are very simple, being little else than 
a hiss. 

474. In birds, the situation of the vocal organ is very 
different. The trachea opens into the pharynx, as in rep¬ 
tiles, by a mere slit, but the most essential organ is at the 
lower extremity of the trachea, near its division into the 
bronchi. This apparatus, which seems to be a kind of 
drum, is variously formed in different species. In jig. 65 



Fig. 65.—Larynx of a spe- Fig. 66.—Larynx of Rc 

cies of Duck. 

c, trachea; b, a kind of bony drum; c, bronchial tubes. 


Fig. 66.—Larynx of Rook. Fig. 67.— Vertical 

SECTION OF THE SAME. 


is a representation of the larynx of a species of duck; 
jig. 66 represents the larynx of a rook; and jig. 67 a sec¬ 
tion of the same. At a, in each of the above figures, is 
seen the larynx; at Z>, a sort of bony drum; and at c, the 
bronchial tubes. In the most esteemed singing-birds these 
parts are much more complicated than in birds not distin¬ 
guished for their vocal powers. 

475. In man and the mammalia, the vocal organ is situ¬ 
ated at the upper part of the windpipe, and is called the 

Where is it produced in reptiles ? How are the vocal organs situated in 
birds ? What does the apparatus resemble ? In what birds is it most com¬ 
plicated? Where is the vocal organ situated in man, and what is it called ? 
From what does it receive its peculiar form ? 








236 


CLASS-BOOK OF PHYSIOLOGY. 


larynx. The larynx receives its peculiar form from foul 
cartilaginous pieces, called the thyroid , the cricoid and the 
arytenoid cartilages. 




Fig. 69.—Vertical Sec¬ 
tion of the Larynx.— 
ar , arytenoid cartilages; 
v , ventricle of the glottis; 
e , epiglottis. The other 
references as before. 


Fig. 70.—Front View 
of the Larynx.— 
The interior wall is 
marked by the lines 
a, a, ft, ft,; /i, inferior 
ligaments of <the glot¬ 
tis, or vocal cords; 
Is , superior ligaments- 
The other references 
as before. 


Fig. 68.—Human Larynx, 

Viewed sideways.— A, hy¬ 
oid-bone ; l , point of origin 
of muscles of the tongue; t, 
thyroid cartilage; a , pro¬ 
jection in front, commonly 
called Adam’s Apple; c, 
cricoid cartilage; tr, tra¬ 
chea ; o, posterior side of 
the larynx, in contact with 
, the oesophagus, 
y 

476. The thyroid, (fig. 68,) is much the largest and is 
composed of two symmetrical halves, which meet in front, 
and form the proturberance in man called “ Adam’s Apple.” 
It rests below on the cricoid cartilage, and is connected 
above with the hyoid-bone of the tongue (h). 

477. The cricoid cartilage (c), which is placed below the 
thyroid (t), is the base of the larynx; it has the form of a 
ring, and is much deeper behind than in front. 

478. The arytenoid cartilages are two small cartilaginous 
bodies, placed upon the upper surface of the back of the 
cricoid cartilage, where there is an open space Left between 
the two halves of the thyroid cartilage. When joined 
together, the arytenoid cartilages resemble the mouth or 
spout of a pitcher. 


Which of the cartilages is the largest ? Of what is it composed ? What 
protuberance does it form? What is aboye and below the thyroid cartilage? 
Where is the cricoid cartilage placed? What is its form? What are the 
arytenoid cartilages? How are they placed? What do they resemble when, 
joined together? 














THE VOICE. 


237 


479. The chordce vocales , or vocal cords, (a, a, fig. 71,) 
which are the instruments principally concerned in the 
production of sound, and also in the regulation of the 
aperture through which the 
air passes into the trachea, 
are stretched across from 
the arytenoid cartilages to 
the interior angle of the 
thyroid cartilage. By the 
meeting of the vocal cords 
in front, and their separa¬ 
tion behind, the aperture 
has the form of a Y, but by 

■ t i n .- t J Fig . 71.—Bird’skyk View of Human Larynx, 

the drawing together of the from above, 

arytenoid cartilages until the cords touch, the aperture is 
completely closed. In this manner, the amount of air per¬ 
mitted to pass the larynx is regulated, and a protection af¬ 
forded against the entrance of solid substances, though there 
is the additional guard of the epiglottis, which is pushed 
down in the act of swallowing upon the open space above. 

480. In the ordinary acts of inspiration, the arytenoid 
cartilages are wide apart, so that the aperture between the 
vocal cords is as large as possible; but in the production 
of vocal sounds the aperture is narrowed, and the vocal 
cords made tense, so as to vibrate with the passage of air, 
in a manner resembling the vibration of the tongue of an 
accordeon, or the reed of a clarionet. The different sounds 
are caused by the different degrees of tension of the vocal 
cords. When the tension is feeble, the tone will be grave 
and dull, and when it is great, the tone will be acute. 

481. The tension of the vocal cords is regulated by the 

What are the vocal cords, and how are they situated ? What is the form 
of the aperture between the vocal cords'? How is it closed? Of what other 
use is it besides to regulate the passage of air ? What other guards has the 
larynx ? What is the condition of the aperture in the ordinary acts of inspi¬ 
ration, in the production of vocal sounds? What does the vibration of the 
vocal cords resemble? How are different sounds caused? What tone is 
produced when the tension is feeble ?—when it is great ? 

17 






238 CLASS-BOOK OF PHYSIOLOGY. 

will with most remarkable precision, and without any con¬ 
sciousness on the part of the individual of the means by 
which the desired result is produced. The average length 
in the male in a state of repose is about T Wths of an inch, 
while in the state of greatest tension it is about T VVths 
of an inch, making a difference of yVo^hs or |th of an inch. 
In the female the difference is less than }th of an inch. 
In this space of yth or yth of an inch, there cannot be less 
than two or three hundred different degrees of tension in 
what may be called a natural voice, while in a voice highly 
cultivated, as in some celebrated vocalists, there must be a 
much larger number—perhaps from one to two thousand. 

'482. Loss of voice, such as occasionally occurs in pub¬ 
lic speakers, is caused, not by “ bronchitis ,” as is generally 
supposed, but by relaxation of the vocal cords to such an 
extent as to lose all control over the size of the aperture 
between them. In ordinary colds, these cords are some¬ 
times slightly inflamed, producing hoarseness. In inflam¬ 
mation of th j vocal cords, the mucous membrane which 
lines the larynx, the trachea, and not unfrequently the 
bronchi, may be similarly affected, and hence the disease 
is commonly called “ bronchitis .” 

483. The voice and the power to produce articulate 
sounds, by which man communicates ideas to his fellows, 
is one of the most remarkable faculties in his possession, 
and one in which he is vastly superior to all other animals. 
By cultivation, the voice can be made greatly to surpass 
its natural powers, and increase its capacities for contrib¬ 
uting to man’s usefulness and pleasure, as a social being. 

How is the tension of the vocal cords regulated ? Have we any conscious¬ 
ness of the tension of the vocal cords? What is their average length in the 
male in a state of repose?—in the greatest tension? What is the difference 
in the female ? How many different degrees of tension are there in a natural 
voice?—in a highly cultivated voice? How is loss of voice caused? What 
other parts are sometimes affected when the vocal cords are inflamed? What 
is said of the power of producing articulate sounds? How may the voice be 
greatly improved ? 

































PLATE XXIII 


THE HUMAN FORM. 


Figure 1.- A Lady writing, and resting on her left elbow, with the right shoulder 

raised. 

Figure 2. - A Lady writing, in a Correct Position. 

Figure 3.- A Boy bent forward too much in writing. 

Figure 4. - A Boy resting on his left elbow. 

Figure 5.- A Boy writing in a Good Position. 

Figure 6.- A Good Attitude in standing. 

Figure 7.- A Man walking erect. 

Figure 8.- A Man stooping while walking. 

Figure 9.- A Round-shouldered or Consumptive Form , caused by the habit of 

indulging in such attitudes as represented in figs. 3 and 8. 

Figure 10. - A Lady riding, with her spine bent in such a manner as to produce 

curvature. 

Figure 11. - A Lady riding correctly. 

Figure 12. - A Boy at School, on an old-fashioned bench , so high that his feet cannot 

touch the floor, and without any support for the back. 

Fiqure 13. - A Boy at School, in a chair, just right — easy, convenient, and perfectly 

adapted to his comfort and health. 

Figure 14. - A Perse i bolstered up in Bed, in such a manner as to form a curvature 

of the spine. 

Figure 15. - A correct position in Bed. 



TL.xxnr, 




















































































































































THE HUMAN FORM. 


243 


CHAPTER XV. 

THE HUMAN FORM. 

484. The sublime privilege of standing and walking 
erect has been exclusively granted to man, and has always 
been given as one of those characteristics that indicate his 
vast superiority over all other animals. An erect form is 
therefore equally essential to the gracefulness and dignity 
of his external appearance, and to the health of the vari¬ 
ous internal organs which perform the vital functions. 

485. The man whose attitude is erect and commanding, 
has a nobleness of appearance that never fails to commend 
him to our respect and esteem; while he who walks with 
his face to the earth, as if bowing beneath a burden of 
guilt, or stooping to some debasing act that leads him to 
shun the face of other men, has an air of inferiority, and 
seems to inspire more of contempt or pity than of ad¬ 
miration. 

486. An erect attitude, and an open breast, is of no less 
importance to health than to personal appearance. For 
any deformity which can affect in any degree the form of 
those cavities which contain the organs of circulation, 
respiration, and digestion, must be more or less prejudicial 
to the perfect action of those vital organs. 

487. Deformities are sometimes the result of unavoid¬ 
able disease of some of the bones, but they are generally 
caused by the habitual indulgence in improper positions. 

488. During childhood the bones are soft and pliable, 
and easily accommodate themselves to any position which 
is habitual. Thus, the bone of the thigh is often perma- 

What has always been given as one of the characteristics of man ? What 
Is said of the importance of an erect form ? What impression does a man of 
erect form make on us?—one of a stooping form? What must be the effect 
upon health of any deformity of the cavities which contain the vital organs? 
How are deformities usually caused ? What is the co dition of the bones 
during childhood ? How may the bone of the thigh be bent ? 

17* 


244 


CLASS-BOOK OF PHYSIOLOGY. 


nently bent by compelling children to sit on a bench so 
high there is no support for the limbs, except at the centre 
of the thighs, which rest on the edges of the seat, as in jig, 
12, Pl. XXIII. 

489. The most common deformities are those of the spine 
and ribs. The ribs are perhaps more easily changed in 
form than other bones of the body. They are long slender 
bones, attached to the spine, by ligaments which admit of 
free motion,to the breast-bone,by flexible cartilages. Their 
very structure is such, that the constant pressure of the 
clothing, day after day, needs to be only very slight to 
bend the ribs downward and inward, as represented in jig. 
6, Pl. XXIV.; and it is not necessary that there should 
be very great strength of ligature, or any repeated acts o* 
violence, to materially diminish the capacity of the chest, 
provided a sufficient length of time be allowed to bring 
about the result in a genteel way. 11 Snug-jitting” dresses, 
from fourteen to twenty, are the only appliances needed 
to make a young lady sadly deformed in chest for life. 

490. The deformities of the spine are caused in a variety 
of ways. The spinal column is composed of twenty-six 
separate bones, placed one above the other, and separated 
from each other by a layer of elastic cartilage. The 
spine is maintained in the erect attitude by the action of 
numerous muscles and ligaments. When these become 
weakened by inaction, or by the constant pressure of dress, 
some portion of the spine is allowed to bend either for¬ 
ward or backward, or to the right or left side. An equal 
portion above or below bends in an opposite direction, 
thus forming two curves. The elasticity of the cartilages 

What are the most common deformities ? What bones of the body are 
more easily changed in form than any other 1 ? Describe the ribs, and the 
manner they are attached to the spine and the breast-bone. How are the 
ribs effected by tight dress? How much pressure is necessary to produce 
deformity of the ribs? How may a young lady be deformed for life? How 
are the deformities of the spine caused ? Describe the spinal column. How 
is it maintained in the erect attitude ? What takes place when the muscles 
become weakened? How does the deformity become permanent? 


THE HUMAN FORM. 


245 


is such that they very soon yield to any position which 
becomes habitual, and thus the deformity gradually be¬ 
comes permanent. 

491. The same curvature of the spine may be effected 
by the habit of inclining to one side or the other while 
sitting, and whenever the habit is formed, there is a con¬ 
stant disposition to persist in it. The habit, not unfre¬ 
quent, commences in resting one elbow, usually the left, 
on the desk at school, and very soon the same attitude is 
observed at the centre-table at home; then follows the 
habit of reclining in bed in such a manner as to favor the 
same form of the spine. Little by little, the spinal column 
deviates from a perpendicular line till there is a permanent 
deformity. Artizans, clerks, writers, and persons whose 
occupations require the use of the right hand chiefly, are 
exceedingly liable to a slight curvature, with marked 
prominence of the right shoulder-blade, unless constant 
care is observed to prevent it. Teachers and parents can¬ 
not be too vigilant of the habits of those committed to 
their charge. The seats in school-rooms should be so 
constructed as to favor correct positions. When a child is 
compelled, for the want of any proper support, to sit sev¬ 
eral hours each day in a bent position, as represented in 
fig. 12, Pl. XXIII., the anterior edges of some of the car¬ 
tilages will be absorbed and become thinner, and at adult 
age, he will stand and walk as represented in figs. 8 and 9, 
Pl. XXIII. 

492. Youth should always be furnished with such recre¬ 
ation as shall call into exercise the various muscles of the 
body. Time for amusement is not alone sufficient; such 
a variety should be afforded at every school and seminary 
as shall call into vigorous use the muscles of the limbs, 
the arms, the body, and the chest. Facilities for exercise 

In what other way may curvature of the spine be caused ? How does the 
habit of inclining to one side frequently commence 1 With what kind of exer¬ 
cise should youth always be furnished ? Is time for amusement sufficient I 
What parts should be exercised in amusement 1 


246 


CLASS-BOOK OF PHYSIOLOGY. 


similar to those represented in figure 9, Plate XXIV., 
should be considered as belonging to the necessary fixtures 
which are indispensable to every well-regulated school. 
Teachers, too, would not only take better care of their 
own health, but would increase their usefulness to those 
committed to their charge, if they would consider it not 
beneath their true calling to give practical lessons in re¬ 
gard to the physical as well as the intellectual exercises of 
their pupils. Too little attention is devoted to the phys¬ 
ical education of the young, in most of our institutions of 
learning, and it is to be hoped that, with a more general 
diffusion of the principles of physiology, this most essen¬ 
tial element for the future usefulness and well-being of 
the young will cease to be neglected. 














PLATE X X I Y 


HUMAN FORM. 


Fioure 1 .- A Lady reading , in a good position. 

Figure 2. - A Lady leaning forward, and resting on one elbow , in aposition favoring 

lateral curvature of the spine. 

Figure 3. - A Lady sewing , in a good position. 

Figure 4. - A Lady occupying such aposition in sewing as to produce anteroposterior 

curvature of the spine. 

Figure 5. - Outlines of a Female Figure , after it has been permanently remodelled by 

fashionable dress. 

Figure 6. - Part of the Skeleton of the same } with the thorax reduced to about half its 

■natural size. 

Figure 7.- Outlines of a Natural Female Figure. 

Figure 8.- Part of the Skeleton of the same. 

Figures 9 and 10.- Public School , with Play-grounds for Boys and Girls , supplied 

with appropriate facilities for recreation and exorcise. 


f 




Tio. 9 

c5 




















































































































































































































































































































































































































































APPENDIX. 


THE AIR WE BREATHE. 

1. The earth we inhabit, is surrounded by an atmosphere of 
air, not less than 45 miles in height. Its pressure, or weight at 
the level of the sea, is allowed to be 14 pounds to the square inch 
of the earth’s surface. Allowing the surface of a man’s body of 
medium size to be fifteen square feet, or 2160 square inches, he 
suffers the enormous pressure of more than fifteen tons. Still, 
as the pressure from within and without is equal, it is unper¬ 
ceived except by its variations. The pressure is the greatest at 
the level of the sea, and diminishes as we ascend high mountains. 
The air floats around the earth in almost perpetual motion, and 
produces gentle breezes, winds, gales, and tornadoes. 

2. Atmospheric air, though apparently a simple element, is a 
mixture of different gases. Its constituents, by weight, are— 
oxygen, 23.02 parts, nitrogen, 76.98 parts, and a portion of car¬ 
bonic acid, varying in amount from to T Aa 

OXYGEN. 

3. Oxygen is the only sustainer of animal life. It unites 
with nearly every substance on the face of the earth with more 
or less intensity. When it combines rapidly with any substance 




252 


CLASS-BOOK OF PHYSIOLOGY. 


it produces combustion—when slowly, oxydation or rusting. A 
piece of wood or charcoal, having on it only the slightest spark 
of fire, will burn with great brilliancy when plunged into pure 
oxygen. A common watch-spring will burn with a sparkling 
light, if one end is coated with sulphur, and plunged into this 
gas the instant it is ignited. 

4. When animals breathe pure oxygen, all their functions are 
increased in activity, and the entire machinery of life is propelled 
beyond its natural velocity. Man is dependent every moment of 
his life on the presence of oxygen in the air he breathes. It is 
constantly combining with the tissues to form carbonic acid and 
generate heat. It is this which imparts to the blood its life- 
giving properties, and removes from it those impurities which are 
constantly formed by the decomposition of the tissues, and which 
would soon destroy life if they were allowed to accumulate in the 
body. The brain, which is the controlling organ of the body, is 
dependent for its energy and power on a due supply of pure oxy¬ 
genated blood. 

5. When oxygen is inhaled freely, it quickens the circulation, 
exalts the vital functions, and imparts an agreeable stimulus to 
the mental powers. In breathing an excess of oxygen, men live 
too fast, and burn away with intense brilliancy, like the taper 
which is plunged into it. But, when they deprive themselves 
as multitudes constantly persist in doing, of the natural quantity 
of oxygen in the air they breathe, all the powers of life, droop 
and languish, and the tone of health is gradually lowered till 
some susceptible organ yields to disease. 

NITROGEN. 

6. Nitrogen is supposed to be useful mainly as a diluent of 
oxygen. It does not support combustion or animal life, though 
there is no reason to suppose that it has any pernicious or poi¬ 
sonous properties. A taper plunged in it goes out because there 
is nothing to support combustion. Animals droop and die in it 
from exhaustion. 


APPENDIX. 


253 


CARBONIC ACID. 

7. When pure, carbonic acid is a most active and fatal poison, 
destroying animal life and extinguishing flame, not from the ab¬ 
sence of oxygen, but from the presence of active qualities, which 
are destructive to life and to combustion. If inhaled pure, it 
produces a spasm of the throat, and causes instantaneous death; 
if it is sufficiently diluted to be received into the lungs, it acts 
as a narcotic, and thus destroys life. 

EFFECTS OF BREATHING CARBONIC ACID. 

8. Pain in the head, drowsiness, languor, and a sense of 
fatigue, the mildest symptoms of its poisonous effects, may be 
experienced in breathing air which contains only one part in one 
hundred of carbonic acid. In three or four parts lights burn 
dimly, and are extinguished in five or six. Six or seven parts 
will produce serious injury to the health, and ten parts prove 
fatal to life. Persons who confine themselves most of the time 
in apartments containing only a small excess of carbonic acid, 
acquire a pale, sallow, and sickly complexion, and ultimately be¬ 
come subject to colds, coughs, bilious complaints, scrofula, or 
consumption. Mechanics, artisans, and shop-keepers, who occupy 
in most of our cities close and unventilated shops by day, and, 
if possible, still closer bed-rooms by night, are twice as liable to 
consumption alone as those who spend most of their time in the 
open air. According to the Report of the Sanitary Commission 
of Massachusetts, 1850, the number of females, compared with the 
males, who die of consumption in the country towns, is nearly two to 
one, while in the cities, where the males are confined in-doors 
more closely than the females, the number of deaths among the 
males is the largest. 

FORMATION OF CARBONIC ACID. 

9. Carbonic acid is evolved from burning fuel, lights, open 
furnaces, limekilns, &c., and it may be formed in large quantities, 
by pouring muriatic acid on marble, or carbonate of lime. It 


254 


CLASS-BOOK OF PHYSIOLOGY. 


is also a natural product of respiration, and is exhaled from the 
skin. It is estimated that about four and a half per cent, of the 
air, as it comes from the lungs in natural respiration, is carbonic 
acid, making on an average about twelve to fifteen cubic feet per 


day. 


10. During the same period, from three to five cubic feet of 
carbonic acid escapes from the skin, making in all some fifteen 
cubic feet daily. But it is a remarkable fact, that if the air 
which is breathed be previously impregnated with carbonic acid, 
the amount which is added to the respired air becomes less and 
less, as the impurity of the air increases. Thus, in a single 
instance, when fresh air was taken in at each respiration, 32 
cubic inches of carbonic acid were exhaled in a minute, while only 
9.5 were emitted in breathing air, which had been previously 
respired. Some efficient means of supplying pure air is therefore 
demanded in every apartment where carbonic acid is found. 


WATERY VAPOR. 

11. Besides the usual estimate of carbonic acid, the respired 
air is found to contain some twenty ounces per day of watery 
vapor. This vapor, however, is not pure water, it contains car¬ 
bonic acid, volatile substances, and animal matter. The breath of 
some individuals possesses an exceedingly offensive and fetid 
odor from the animal impurities with which it is charged. Tur¬ 
pentine, alochol, camphor, garlics, and other odorous substances, it 
is well known, can be detected in the breath for several hours 
after they have been taken into the stomach. During the progress 
of febrile diseases, or during temporary derangement of the 
stomach, the offensive odor of the breath is often greatly 
increased. 


EXCRETIONS OF THE SKIN. 

12. The natural excretions of the skin also contribute to the 
impurities of the atmosphere. The amount of impurities which 
pass off from the skin is by no means uniform, since they must 
of necessity vary with the temperature of the air, the amount of 



APPENDIX. 


255 


fluid taRen, the habits of exercise, and various other circum¬ 
stances. As a general estimate, the excretions of an adult will 
not be less than thirty-two ounces each day, while they are often 
as high as five pounds. Of this, the largest proportion is a 
watery vapor, which escapes in the form of “ sensible or insensi¬ 
ble perspiration” but about one per cent, consists of solid sub¬ 
stances, which are the products of the decomposition constantly 
taking place in the tissues. The peculiar odor of perspiration is 
owing to the effete matter which it contains, and is sometimes 
very offensive on persons who neglect daily ablution. 

13. The total quantity of impurities which are daily given off 
by an adult, are on an average as follows :— 

Carbonic acid . . . . 14 to 20 cubic feet 

Watery vapor . . . . 2 to 5 pounds. 

Effete animal matter . . 1 to 2 ounces. 

According to Dr. Charles A. Lee, each person vitiates, or 
renders unfit for respiration nearly four cubic feet of air every 
minute.? It is therefore necessary in order to preserve the 
purity of the air, that at least an equal quantity should be 
changed every minute. 


VENTILATION. 

14. There is no subject, directly connected with the preserva¬ 
tion of health, in reference to which there is so much popular 
ignorance and indifference as ventilation. All men understand 
the necessity and importance of providing for themselves food and 
drink; but for air, the essential element of existence, they make 
no provision ; yet men have been known to live five weeks with¬ 
out food, but a person wholly deprived of air will not live five 
minutes. We have no appetite and no instinctive impulses which 
protest against an insufficient supply of air, as against want of 
food and drink; nor do we realize that bad air is a slow poison, 
the breathing of which as surely injures the health, as the 

* Copland’s Practical Medicine, page 138. 



256 


CLASS-BOOK OF PHYSIOLOGY. 


habitual use of arsenic, prussic acid, or any other poison. Our 
indifference, in a matter of so much vital importance, can be 
accounted for only on the supposition that we are slow to believo 
that we can be injured by any agent which does not produce an 
immediate and sensible effect. 

15. But it is nevertheless true, that the breathing of impure 
air is a fruitful source of impaired health and disease. Air which 
has been breathed over and over again in our parlors, sleeping 
apartments, school-rooms, public halls, and churches, becomes’ 
charged with the dead animal matter which is constantly given off 
by the skin and lungs, and with carbonic acid gas, the natural 
product of respiration, and is as truly poisonous as the most loath¬ 
some substance in nature. Air thus poisoned, is as unwholesome 
for the purpose of respiration, and would be as repulsive, if our 
senses could appreciate it, as decayed animal flesh for the purpose 
of mastication and digestion. 

16. It is now well established, that one of the common causes of 
typhus fever is the effete matter of the human body, accumulated 
and long retained in private dwellings. Typhus fever, dysentery, 
and the cholera, when they prevail as epidemics, not unfrequently 
take their origin in the impure air which is breathed in camps, in 
the holds of emigrant ships, and in the abodes of squalid poverty. 
Though these malignant diseases may not often be generated 
spontaneously in the unventilated apartments of* the affluent, still 
the health may be gradually impaired, and the seeds of disease 
insidiously implanted in the constitution. The blanched features, 
the pale and cadaverous countenance, and the impaired health, 
with which multitudes come forth from their winter-quarters in 
the spring, testify very plainly to the pernicious influence of bad 
air. 

17. Till within the last half century, almost the only heat 
ing apparatus in use was a fire-place, with a depth of from three 
to four feet, and and a width of from six to eight, and a flue of 
equally liberal dimensions. When one of these mammoth fire¬ 
places was filled with wood, and burning briskly, a volume of 
rarefied air was constantly driven up the chimney, sufficient to 





APPENDIX. 


257 


exhaust in a few minutes the air of almost any room. Under 
such circumstances, there could hardly fail to he a constant 
supply of unrespired air, so long as the crevices about the doors 
and windows were sufficiently open to supply the draft up the 
chimney. The imperfect architecture of the houses, and its 
liberal dimensions, made the old fashioned fire-place a noble 
ventilator. 

18. With the disappearance of the forests, and the constantly 
increasing scarcity of fuel, this noble ventilator has given place 
to small Franklins, open grates, and air-tight stoves. An open 
fire, in any form, has some value as a ventilator, though it is not 
sufficient for all the purposes of ventilation. When this is sur¬ 
mounted by a flue of good draught, it will draw off a portion of 
the air from the bottom of the room, and thus secure a change of 
air. But an open fire is liable to this objection, that while the 
cold air which enters the windows and doors falls to the floor, and 
flows along to the fire, and becoming heated, rises in the flue, the 
air that is to be respired in the upper part of the room suffers 
but little change, and is breathed over and over again, till it is 
unfit for respiration. 

19. But an open fire is vastly better than the air-tight stove, 
which produces little or no change of air, except the very small 
quantity required to support combustion. 

HOT AIR FURNACES. 

20. Hot air furnaces and ventilating stoves are quite modern 
inventions, and may be regarded as affording one very essentia] 
condition of ventilation, namely, a constant supply of pure air. 
But the system of heating by introducing air that has been pre¬ 
viously warmed is not perfect, without some means of exhausting 
the impure air. 

21. Air, as it is delivered from most hot-air furnaces, is at a 
much higher temperature than the air of the room, and, when 
admitted through large registers, rushes to the ceiling and forms 
a stratum of heated air in the upper part of the room, leaving 





258 


CLASS-BOOK OF PHYSIOLOGY. 


the air near the floor quite unchanged. If the heated air be in* 
troduced through numerous small openings in the floor, and j] 
allowed to rise to the ceiling and then pass off, pure air will be 1 
secured in all parts of the room. 

22. Under any arrangement now in use for producing arti- 
ficial heat during winter, some means of ventilation must be 
regarded as indispensable. A great variety of methods have j 
been proposed, but that is to be preferred which is most simple, 
constant and uniform. The most important principles to be ob- 1 
served may be reduced to the following rules. 


RULES FOR VENTILATION. 

23. 1st. Each room should be provided with some means for 
introducing a constant and uniform supply of pure air. 




During winter, it will he found most economical, as well as most agreea¬ 
ble, to introduce air which has been previously warmed. 


24. 2d. Each room should be provided with a flue or ventila¬ 
tor, of a capacity proportioned to the size of the apartment and 
the number of its occupants, with two valves or registers for the 
escape of impure air, one near the ceiling, and the other near the 
floor. 

25. 3d. In private apartments of good size, which are occu¬ 
pied by only a small number of persons, the supply of pure air 
should not be less than four cubic feet per minute for each per¬ 
son. In school-rooms, churches and public halls, from eight to < 
ten cubic feet per minute will be required. 

26. 4th. The valve in the ventilator near the ceiling should 
be allowed to remain open, and the valve near the floor be closed, 
when a room is too warm, and when it is heated by an open fire 
or a close stove, and during warm weather. 

27. 5th. The register near the floor should remain open when 
the room is warmed by heated air, introduced by a hot air fur¬ 
nace, or from a ventilating stove. 

28. 6th. Each ventiduct should be so constructed as to secure 
a constant draft. 



APPENDIX. 


259 


This may be accomplished either by heating the ventiduct, or by sur¬ 
mounting it with an exhauster. The ventiduct may be heated by a cast- 
iron smoke-pipe passed up through it, or by separating it from the smoke- 
fine by a thin partition. 

29. 7th. In summer, when it is necessary to open the win¬ 
dows to secure ventilation, they should, if possible, be open at 
the top and bottom, and on opposite sides of the room, though 
no person should remain directly in the current of cold air, unless 
protected by suitable clothing, or by active exercise. 

DIET. 

30. Man is less uniform in his diet, and suffers more in con¬ 
sequence of it, than any other animal. All other animals are 
directed by instinct to select only those substances which are 
best adapted to their wants. Man is endowed with reason to 
enable him, by the exercise of thought and reflection, to make 
his choice of the bounties of Providence. He should, therefore, 
select his daily food with as much forethought and care as he 
would select the materials for his dwelling. He should consider, 
not what will gratify his taste, but what will build up and 
strengthen his bodily structure, and secure most perfectly the 
highest and most permanent enjoyment of all his faculties. 

CHOICE OF FOOD. 

31. The kind of food which each individual should select is 
by no means uniform. The climate, the season of the year, the 
occupation, the temperament, the age, the habits of life, and vari¬ 
ous other circumstances, which might be enumerated, demand 
modifications of diet. 

MODIFICATIONS OF AGE 

32. The constituent elements of the body are not found in 
the same relative proportions at different periods of life, or in 
different individuals of the same age. In middle life the mus¬ 
cular system predominates, and the body is remarkable for tho 


260 


CLASS-BOOK OF PHYSIOLOGY. 


compactness of its fibre, its strength, and its power of endurance 
In the child there is an excess of fluids, which renders the body 
more plump and round, and the form beautiful, though more frail 
and delicate than at a later period. In advanced age the soft 
tissues have become greatly diminished, and the form wrinkled 
and wasted. 

TEMPERAMENT AND OCCUPATION. 

33. In different individuals of the same age, there is a dissimi 
larity of structure and constitutional peculiarities, quite as remark¬ 
able as in those of different ages. One possesses large and pow¬ 
erful muscles, by which he is enabled to accomplish a great 
amount of physical labor, and to perform remarkable feats of 
strength and endurance. Another, with a larger brain, but with 
smaller and weaker muscles, has “ a lean and hungry look,” and 
is distinguished by the powers of his intellect. Another is “ fat 
and sleek-headed,” and follows a life of ease and indolence. In 
short, there are almost as many peculiarities of constitution, tem¬ 
perament and occupation, as there are individuals. Each person 
should, therefore, have a diet adapted to his own peculiarities. 

CLIMATE. 

34. The inhabitants of cold climates require those articles of 
food which produce the largest amount of animal heat; such as 
oil, tallow, and fat meats, which contain from 66 to 80 per cent, 
of carbon. The natives of the arctic regions consume enormous 
quantities of fat and oil, and seem to relish them as great luxu¬ 
ries. The inhabitants of tropical regions subsist mainly on rice, 
fruits, vegetables, and lean meats. It would be impossible to 
live in Greenland on the plaintain and rice of the Hindoo, or in 
Hindoostan on the seal fat and whale oil of the Greenlander. 

S E>A SON OF THE YEAR. 

35. In temperate climates we require different kinds of food 
at different seasons of the year. In winter we consume larger 






APPENDIX. 


261 


quantities of fat meat and other carbonaceous food, and in sum¬ 
mer more fruit and vegetables. Were we to indulge in summer 
in the same diet which we might find highly conducive to health 
during winter, the system would very soon become burdened 
with an excess of carbonaceous matter, and induce congestive 
and inflammatory diseases. It is, therefore, highly important 
that each person should possess some knowledge of the properties 
of different articles of diet, and select, from time to time, such 
as he thinks most suitable for his own organization. 

PROPERTIES OF ALIMENTARY SUBSTANCES. 

36. Different substances are nutritious in proportion as they 
yield, when digested, those elements which are found to exist in 
the various tissues of the body. Animals do not possess the 
power of forming new elements, or of converting one element into 
another, and it necessarily follows that the elements of their 
growth and nutrition must be derived from the food which they 
take. The largest part of nearly all the substances which make 
up the human body, are composed of oxygen , hydrogen , nitrogen 
and carbon , and different substances are regarded as nutritious 
in proportion as they furnish these essential elements of all ani¬ 
mal organization. In general, those substances may be regarded 
as the most valuable articles of diet which furnish, with tho 
greatest facility of digestion, the largest amount of these elements. 

MILK. 

37. Milk is regarded, perhaps correctly, as the simplest and 
plainest kind of food. Unlike almost any other article of diet, 
it embraces all the necessary elements for the nutrition of the 
body, and contains these elements in a form peculiarly adapted 
to the young of all the mammalia. Perhaps no one article of 
food is more widely diffused among all races of men than this. 
The Laplander, within the Polar Circle, is provided with milk as 
an important part of his diet by the reindeer. The Arabs, in 
the burning desert of the tropics, obtain this nutriment from 
their camels, their sheep, and sometimes from their goats. In 


262 


CLASS-BOOK OF PHYSIOLOGY. 


all civilized countries, the cow is to be found—in the densely 
populated cities,—and by the log-cabin of the pioneer. Cow’s 
milk is composed of— 


Casein,.. . 448 

Butter, 313 

Sugar of Milk,. 4*77 

Various Salts,. *60 

Water,.87*00 


38. Milk, being furnished by nature as the only food for the 
young of the mammalia during a certain period of their exist¬ 
ence, contains all the elements necessary for the nutrition and 
growth of the body. “ Out of the casein are formed the albumen 
and fibrin of the blood. The butter serves for the formation of 
fat, and contributes, with the sugar, to support animal heat by 
yielding carbon and hydrogen to be burnt in the lungs. The 
earthy salts (phosphate of lime, &c.) are necessary for the devel¬ 
opment of the bones. The iron is required for the blood-corpus¬ 
cles and the hair.” Milk is a highly useful and valuable article 
of food, as well for the adult as the child—for healthy indivi- 
duals, as for invalids and convalescents. 

FISH. 

39. An almost endless variety of food is furnished to man 
by the numerous genera and species of fish. Among some na¬ 
tions, it constitutes the major portion of their diet. Fish are 
less nourishing and less satisfying to the appetite than the flesh 
of either birds or the mammalia. Those kinds of fish which 
abound in oil, as salmon and eels, are more nourishing, but less 
digestible than haddock, sole, flounder, cod or turbot. 

40. The digestibility of fish is very much diminished by the 
process of salting, smoking, and drying. The watery portion is 
thereby diminished, causing a larger amount of nutritive matter 
to be taken in proportion to the bulk. A fish diet is less sub¬ 
stantial than either butcher’s meat or poultry. It may be em¬ 
ployed when the digestive organs are unable to assimilate stronger 









APPENDIX. 


263 


kinds of aliment, when it is necessary to avoid the stimulus which 
butcher’s meat communicates to the system. Fish is better 
adapted to the wants of the system during the warm season than 
the cold; since the flesh of the more digestible kinds is less 
stimulating, and contains a smaller proportion of carbonaceous 
or heat* producing elements. The quantity-of nutritive matter 
found in some kinds of fish has been stated as follows :— 

100 parts of Muscle. Water. Albumen or Fibrin. Gelatin. Total of Nutritive Matter. 


Cod, . . 

. *79 

14 

1 

21 

Haddock, . 

. 1 2 

13 

5 

18 

Sole, . . 

. 19 

15 

6 

21 


OYSTERS. 

41. Oysters hold a high rank as a delicious and favorite arti¬ 
cle of food, which is easily digested by most persons, though they 
unquestionably disagree with some constitutions. They are more 
easily digested when raw than when cooked, according to the ex¬ 
periments of Dr. Beaumont. 


DIGESTIBILITY OF OYSTERS. 

H. 

M. 

Raw,. 

. 2 

55 

Roasted, .... 

. 3 

15 

Stewed,. 

. 3 

30 


42. During the warmest weather, fish and oysters are both un¬ 
safe articles of diet unless used very soon after they are removed 
from the water. But for those who are favored either with a 
temporary or a permanent residence on the sea-shore, both may 
be regarded as a highly useful and agreeable diet. 

LOBSTERS 

43. Lobsters, though highly esteemed by epicures, are very 
difficult of digestion, and not to be included in the list of articles 
proper to be indulged in by those who prefer health to the grati¬ 
fication of appetite. 




264 


CLASS-BOOK OF PHYSIOLOGY. 


MEAT. 

44. In this country meat constitutes an important part of the 
diet of almost every family. As a general rule, animal food is ; 
more easily digested, contains a greater quantity of nutriment, 
and is more stimulating than any of the varieties of vegetable \ 
food. The following is the composition of the kinds of meat in ! 
most general use. 

100 parts of Muscle. Water. Albumen or Fibrin. Gelatin. Total of Nutritive Matter. 


Bee£ . . 

. 74 

20 

6 

26 

Veal, . . 

. 75 

19 

6 

25 

Mutton, . 

. 71 

22 

7 

29 

Pork, . . 

. 76 

19 

5 

24 

Chicken, , 

. 73 

20 

7 

27 


45. As minuteness of division and tenderness of fibre facili¬ 
tate digestion, young meats are more tender than old. Thus, 
roasted pig, according to Dr. Beaumont’s experiments, was more 
speedily digested than broiled pork. Steak and boiled lamb, 
sooner than boiled mutton. Still, there are some exceptions to 
the digestibility of young meats. Veal, and, with some persons, 
lamb, are slower of digestion than beef and mutton. 

VEGETABLE FOOD 

46. The vegetable kingdom greatly exceeds the animal in the 
number and variety of the aliments which it furnishes to man. 
The chief nutritive principles in vegetables are gluten, starch, 
sugar, gum and oil. The alimentary qualities of different kinds 
of vegetable food will be found to depend on the quantity and 
the proportions in which these principles exist. The composi¬ 
tion of each of these principles is given in the following table : 


Carbon. 
Gluten, 65*22 

Starch, 37*6 

Sugar, 42*85 

Gum, 36*3 

Oil, 77*403 


Hydrogen. Oxygen. 

7*42 21*38 


10*828 

11*481 


Nitrogen. Water. 
15*08 

62*5 

67*15 

63*7 

2*888 






appendix. 


265 


47. It will be seen by the above table that the four essential 
elements, Carbon, Hydrogen, Oxygen, and Nitrogen, which form 
an important part of all animal compounds, are also to be found 
in great abundance in vegetable compounds. It is owing to this 
fact that different animals are nourished equally well on an ex¬ 
clusive diet of either. The lion, tiger, and other animals which 
live exclusively on animal food, give no evidence of being better 
nourished than the deer, the ox, and those animals which subsist 
wholly on vegetable food. But the apparatus for digestion in 
each class is constructed with an evident adaptation to the kind 
of diet on which the different animals subsist. Those animals 
which live on vegetable aliment are provided with organs more 
complicated than those which subsist on the flesh of other ani¬ 
mals. In man, the digestive apparatus is more extensive than 
in flesh-eating animals, but is less complicated than in those 
which are confined to vegetable food alone. Man is therefore 
omnivorous, both in his structure and in his habits. 

48. Instances are not wanting, however, in which men have 
lived in the apparent enjoyment of health on an exclusive diet 
of each. Thus, Sir Francis Head states in regard to the 
Guachos, inhabitants of the Pampas in South America, “ that 
they often continue on horseback day after day, galloping over 
their boundless plains, under a burning sun, and performing 
labors almost of an incredible description. The constant food 
of the Guachos is beef and water. His constitution is so strong 
that he is able to endure great fatigue, and the distances he will 
ride, and the number of hours he will remain on horseback, 
would hardly be credited.” The inhabitants of India and 
most tropical countries subsist almost entirely on a vegetable 
diet. 

49. But the universal tendency of mankind gives preference 
to a mixed diet. The most perfect physical development and 
the greatest intellectual vigor are to be found among those races 
in which a mixed diet is the prevalent habit. 

19 


266 


CLASS-BOOK OF PHYSIOLOGY. 


USE OF FRUIT. 

50. During the warm season, vegetables and fruits may be 
made the means of great mischief or of great good. Perfectly 
ripe fruits and vegetables are highly useful, and well adapted to 
the wants of the system at this season of the year. Yet they may 
become, and often are, a most prolific source of disease. So fre¬ 
quently is this kind of food a cause of bowel complaints, that most 
city physicians discard it wholly from the diet of children not 
under their own personal supervision. Some prohibit their use 
to adults. Vegetables and early fruit that have been long ex¬ 
posed in a malarious or filthy market, or in transportation, are 
unquestionably dangerous articles of food for all persons. Put 
the injurious consequences which follow the use of ripe and whole¬ 
some vegetables and fruit, are in almost all cases the results of 
imprudence. They are either in an improper condition to be used 
as food, or the quantity is too great, or it is taken at improper 
hours. Many families use this kind of food only occasionally, 
and then it forms an important part of a meal, or is indulged free¬ 
ly at other hours. In either case, there is a very great change 
from the usual diet. Instead of a lack ©f refrigerant and laxative 
food, there is now an excess of it. Active fermentation takes 
place in the process of digestion, and results in serious derange¬ 
ment of the whole alimentary canal, which leads to cholera-mor¬ 
bus, diarrhoea, or dysentery. 

51. During warm weather, vegetables and fruit are to be re¬ 
garded as safe only when used as an accompaniment to other 
food. They are not adapted to meet all the wants of the system, 
and therefore should not constitute a full meal at any time. In 
the country, where this kind of food is enjoyed daily, in a proper 
condition to be eaten, injurious consequences are quite rare, and 
then they are the result of excess, or of an indulgence of the ap¬ 
petite at irregular hours. Children are remarkably fond of fruit, 
as well as sugar, and there seems to be in their constitutions some 
inherent demand for these articles. No part of their diet appa¬ 
rently conduces more to their health and happiness, when they 
are allowed it at proper times, and as a portion of their daily 



APPENDIX. 


267 


food. But children are so prone to excessive indulgence in the 
various kinds of fruits, that great caution is necessary to prevent 
the most serious evils. Much care is also requisite to prevent 
imperfect mastication of this kind of food. Orange-peel, and 
the skins and stones of cherries, plums and grapes, are wholly 
indigestible, and often cause serious mischief when swallowed. 

Cucumbers, beets, green potatoes, green fruit of all sorts, 
should be wholly discarded from the diet of children. 

DRINKS. 

52. Water, in some form, is more essential to our existence 
than any of the solid aliments we have considered, and is next in 
importance to the performance of the vital processes, to the air 
we breathe. Water enters into the formation of all the various 
tissues of the body, and constitutes a very large proportion of the 
human system. The blood contains about eighty per cent.; the 
flesh about seventy-six per cent, of water; and of the entire hu¬ 
man body at least seventy-five per cent., or three fourths of its 
weight, is water. The most important purposes in the animal 
economy, are accomplished through this medium. In the blood, 
the solid vital elements are transported by the medium of water 
from one part of the body to another in a form and condition to 
promote the vital changes which are constantly taking place. In 
exhalation, secretion and absorption, the presence of water is in¬ 
dispensable. It acts as a solvent of various alimentary substan¬ 
ces, and thus assists the stomach in the act of digestion. Though 
when taken in large quantities immediately after eating, it dilutes 
the gastric juice, and hinders digestion. Water enters more or 
less largely into the composition of all alimentary substances, and 
is taken into the stomach in a pure state, or forms the principal 
part of the various kinds of drinks in use. 

53. Water is unquestionably the natural drink of adults, and 
meets the wants of the body more perfectly than any or all of the 
artificial liquids which are regarded as improvements on the sim¬ 
ple drink Nature has designed and universally provided for man 


268 


CLASS-BOOK OF PHYSIOLOGY. 


and beast in all parts of the earth. Whenever a man is left to 
the cravings of instinct, unbiased by a vicious appetite, he inva¬ 
riably resorts to water as the natural means to quench his thirst, 
cool his system, and invigorate his wasting strength. “ Next to 
the nutritive fluid furnished by the maternal bosom, water is the 
one taken with avidity by the infant, as, if left to his primitive 
taste, it ever would be by adult man ; and even he who, in the 
madness of his evening revel, drinks deep of the intoxicating 
bowl, and stoutly denies the fitness of water as a beverage, will 
on the following morning entreat for and clasp with eagerness the 
full pitcher of this liquid, which a few hours before he had so reso¬ 
lutely derided. Both interest and recovered reason now suggest 
the choice of the proper beverage ; and, but for the curse of imi¬ 
tation and evil example, their joint influence could never be mis¬ 
taken.” 

54. “ When we say that water is the only fitting drink for man’s 
daily and habitual use, we are sustained by the facts of the case. 
Water is the only liquid which is essential to the formation, de¬ 
velopment, and support of his frame: it is equal to all the ex¬ 
igencies of thirst, for the relief of present inconvenience, and of 
dilution, by mixing with his blood, and other fluids, to prevent 
farther suffering and disease. Water is found in all climates and 
habitable regions of the earth; and Providence has nowhere of¬ 
fered, in fountain, stream or well, in river or in lake, any liquid 
as a substitute for water. To be the universal beverage, it ought 
to be, as it is, every where attainable, and adequate to all our nat¬ 
ural wants,—of appetite, growth, bodily and mental exercise, and 
activity. Even when the health suffers, and the body and mind 
are ill at ease, where is the restorative liquid or agent of any 
kind which can revive and renovate like water,—whether taken 
alone, in its purity, or with some slight saline and mineral impreg¬ 
nation ! It is the beneficent menstruum and conductor of medi¬ 
cinal matter into the blood ; end even when they are refused en¬ 
trance, it readily finds its way, and not seldom accomplishes the 
cure for which they are lauded.” 

55. In fevers and inflammatory diseases, water quenches the 




APPENDIX. 


269 


stimulating quality of the blood, increases its aqueous part, pro¬ 
motes the action of the secreting organs, and is a most efficient 
means for reducing the fever and allaying the burning heat. 

DIGESTIBILITY OF ALIMENTARY SUBSTANCES. 

56. The facility with which different alimentary substances 
are digested, depends on a variety of circumstances. Some kinds 
of food are naturally more difficult j>f digestion than others. This 
is especially the case with all oily or fatty substances, which con¬ 
tain a large amount of nutritive matter in a concentrated form. 
Tenderness of fibre renders the digestive process more easy, and 
therefore all those circumstances which affect the texture of flesh 
have an influence on its digestibility. Violent muscular exertion 
immediately previous to the death of the animal renders the flesh 
more easy of digestion. The flesh of young animals, though more 
tender than that of the adult animal, is frequently not so easily 
digested. Of adult animals, the youngest will be found more ten¬ 
der and digestible than old animals. Vegetables are generally 
more slowly digested than meat. Minute division facilitates di¬ 
gestion : hence, if food is perfectly masticated, the process of di¬ 
gestion will be more rapid than otherwise. 

COOKING. 

57. The art of cooking has as much or more to do with the 
digestibility of food than any circumstance belonging to the food 
itself, or the manner in which it is received into the stomach. 
The immediate object which civilized nations seem to aim at in 
the art of cooking is, the gratification of the palate. The more 
important purpose of promoting digestion is quite a secondary 
object. Cooking, for the most part, produces no chemical change 
in the constitution of food. It simply destroys its organization, 
and softens its texture. 


BOILING. 

58. Boiling is the process best suited to facilitate digestion. 
It softens the fibrous texture of meat, and renders it more solu- 


270 


CLASS-BOOK OF PHYSIOLOGY. 


l>le in the gastric juice, while the oily and more indigestible por¬ 
tions of the meat are melted out. In the case of vegetables, boil 
ing effects the solution of gummy and saccharine substances, and 
sets free the volatile oils. 


roasting. 

59. Roasting and broiling are both regarded as unobjection¬ 
able and next to boiling. Meat, when roasted or broiled, is 
more digestible when well done than when rare—provided it be 
not overdone. When thoroughly cooked, it contains less oil than 
when rare. 


FRYING. 

60. Frying is the most objectionable of all the ordinary pro¬ 
cesses of cooking—for the reason that meat prepared in this way 
contains a larger amount of oil than by any other process. Eggs, 
omelets, pan-cakes, fritters, fish, livers, and other dishes cooked by 
frying, are difficult of digestion for weak stomachs. Butter and 
all fat substances when melted, set free their fixed oils, and be¬ 
come indigestible. Thus, drawn butter, buttered toast, butter 
cakes, pastry, marrow, and suet-puddings, are all difficult of diges¬ 
tion, and u lie heavy on the stomach.” 

PASTRY. 

61. The whole process of pastry-cooking is at war with di¬ 
gestion, and cannot be indulged in with impunity by persons of 
weak stomachs and dyspeptic habits. Articles of food that are 
naturally easy of digestion, when uncombined with other articles, 
become most obnoxious to the digestive organs by being com¬ 
pounded together. Thus, eggs, flour, butter, bread, and sugar, are 
each very wholesome, and readily digested when eaten separately; 
but when the eggs and butter are combined with the flour and su¬ 
gar to form rich cake, the compound may almost defy the powers 
of the human stomach. Eggs, too, when rarely boiled, will not 
offend the most delicate stomachs, but when fried hard in animal 




APPENDIX. 


271 


fat or butter, they are exceedingly difficult of digestion by the 
most vigorous. All compounds, or such as are formed by cook¬ 
ing several simple articles of diet in combination, are found more 
or less indigestible, according to the richness of the compound. 

62. The mean time required for the digestion of different 
articles of diet is shown in the following table : 


TABLE.’ 


Articles of Diet 
Beefsteak 

Pork, recently salted 
Pork, recently salted 
Mutton, fresh. . 

Mutton, fresh . 

Soup, bean 
Chicken soup . 
Aponeurosis 
Dumpling, apple 
Cake, corn 
Oysters, fresh . 

Pork, recently salted 
Pork' steak 
Mutton, fresh . 

Bread, corn 
Carrot, orange. 

Sausage, fresh . 
Flounder, fresh 
Catfish, fresh 
Oysters, fresh . 

Beef, fresh, lean, dry 
Beef, with mustard, &c. 
Butter 

Cheese, old, strong . 
Soup, mutton . 

Oyster soup . 

Bread, wheat, fresh 
Turnips, flat . 
Potatoes, Irish 


* This table is made up fiom the observations of 
lion in the stomach of Aleiis St Martin. 


Preparation. 

n. 

M. 

Broiled 

3 


Raw 

3 


Stewed 

3 


Broiled 

3 


Boiled 

3 


Boiled 

3 


Boiled 

3 


Boiled 

3 


Boiled 

3 


Baked 

3 


Roasted 

3 

15 

Broiled 

3 

15 

Broiled 

3 

15 

Roasted 

3 

15 

Baked 

3 

15 

Boiled 

3 

15 

Broiled 

3 

20 

Fried 

3 

30 

Fried 

3 

30 

Stewed 

3 

30 

Roasted 

3 

30 

Boiled 

3 

30 

Melted 

3 

30 

Raw 

3 

30 

Boiled 

3 

30 

Boiled 

3 

30 

Baked 

3 

30 

Boiled 

3 

30 

Boiled 

3 

30 


Dr. Beaumont on the process oi digee- 





272 


CLASS-BOOK OF PHYSIOLOGY. 


Articles of Diet. 


Preparation. 

II. 

M. 

Eggs, fresh 


. Hard Boiled 

3 

30 

Eggs, fresh 


. Fried 

3 

80 

Greea corn and beans • 


. Boiled 

3 

45 

Beets . 


. Boiled 

3 

45 

Salmon, salted 


. Boiled 

4' 


Beef .... 


. Fried 

4 


Veal, fresh 


. Broiled 

4 


Fowls, domestic 


. Boiled 

4 


Fowls, domestic 


. Roasted 

4 


• Ducks, domestic 


. Roasted 

4 


Soup, beef, vegetables, and bread . Boiled 

4 


Heart, animal 


. Fried 

4 


Beef, old, hard, salted . 


. Boiled 

4 

15 

Pork, recently salted 


. Fried 

4 

15 

Soup, marrow bones 


. Boiled 

4 

15 

Cartilage 


. Boiled 

4 

15 

Pork, recently salted 


. Boiled 

4 

30 

Yeal, fresh 


. Fried 

4 

30 

Ducks, wild . 


. Roasted 

4 

30 

Suet* mutton 


. Boiled 

4 

30 

Pork, fat and lean . 


. Roasted 

6 

15 

Tendon 

. - 

. Boiled 

5 

30 

Suet, beef, fresh . 


. Boiled 

5 

30 

Rice .... 


. Boiled 

1 


Pigs’ feet, soused . 


. Boiled 

1 


Tripe, soused 


. Boiled 

1 


Eggs, whipped 


. Raw 

1 

30 

Trout, salmon, fresh 


. Boiled 

1 

0 

Trout, salmon, fresh 


. Fried 

1 

30 

Soup, barley 


. Boiled 

1 

30 

Apples, sweet, mellow . 


. Raw 

1 

30 

Venison steak 


. Broiled 

1 

35 

Brains, animal 


. Boiled 

1 

45 

Sago .... 


. Boiled 

1 

45 

Tapioca 


. Boiled 

2 


Barley 


. Boiled 

2 


Milk .... 


. Boiled 

2 


Liver, beef’s, fresh 


. Broiled 

2 


Eggs, fresh . 


. Raw 

2 


Codfish, cured, dry 


. Boiled 

2 


Apples, sour, mellow . 


. Raw 

2 











PENDIX. 


273 


Articles of Diet 

Preparation. 

n. 

M. 

Cabbage, with vinegar. 

. Raw 

2 


Milk. 

. Raw 

2 


Eggs f fresh . . 

. Roasted 

2 

15 

Turkey, wild 

. Roasted 

2 

18 

Turkey, domestic 

. Boiled 

2 

25 

Gelatine .... 

. Boiled 

2 

30 

Turkey, domestic 

. Roasted 

2 

30 

Goose, wild 

. Roasted 

2 

30 

Pig, sucking 

. Roasted 

2 

30 

Lamb, fresh 

, Broiled 

2 

30 

Hash, meat and vegetables . 

. Warmed 

2 

30 

Beans, pod 

. Boiled 

2 

30 

Cake, sponge 

. Baked 

2 

30 

Parsnips .... 

. Boiled 

2 

30 

Potatoes, Irish 

. Roasted 

2 

30 

Potatoes, Irish 

. Baked 

2 

30 

Cabbage, head 

. Raw 

2 

30 

Spinal marrow, animal 

Boiled 

2 

40 

Chicken, full grown 

. Fricasseed 

2 

45 

Custard .... 

. Baked 

2 

45 

Beef, with salt only 

. Boiled 

2 

45 

Apples, sour, hard 

. Raw 

2 

50 

Oysters, fresh 

. Raw 

2 

55 

Eggs, fresh .... 

. Soft Boiled 

3 


Bass, striped, fresh 

. Broiled 

8 


Beef, fresh, lean, rare . 

. Roasted 

3 



63. The preceding table cannot be taken with full confidence 
of its accuracy in all cases, since the observations were made 
under a variety of circumstances, which might influence the 
length of time in some instances. The rapidity of digestion, as 
Dr. Beaumont himself shows, varies greatly, according to the 
quantity eaten, the amount and nature of the preceding meal, the 
state of health and of weather, and also the state of the mind. 

VARIETY OF FOOD. 

64. Some variety of food is unquestionably more agreeable, 
and more conducive to health, than a diet limited to one or a 
very few simple articles. Accordingly, we find that, wherever 

12 * 






274 


CLASS-BOOK OF PHYSIOLOGY. 


the condition of men will admit of it, they universally make use Oi 
more or less variety of alimentary substances, and that this variety 
increases very much in proportion to the wealth and ability 
which exists to gratify the desires of the palate, till multiplied 
luxuries become the sources of unnumbered physical evils. 

65. Too great a variety of alimentary substances, whether 
simple aliments or the compounds of skilful cookery, is always 
injurious when it becomes a temptation to excess. Few men who 
habitually burden their stomachs with a little of all the luxuries 
which find a place on many public and private tables, can long 
escape the just punishment of violated physical law. The 
stomach has imposed on it not only the digestion of an excessive 
amount of food, but a great variety of different substances, 
which, collectively, become far more difficult of digestion than a 
meal that is made from a smaller number of articles. In this 
country, the means of living are so abundant, and so easily ob¬ 
tained, that there is a constant tendency to an excessive indul¬ 
gence of the appetite. Thus, a much larger amount of food is 
taken than the wants of the body require, and more than the 
digestive organs have the capacity to dispose of. Second courses, 
served up in every variety of style, to gratify the pride of the 
host, too often overpower the stomachs and stupefy the intellects 
of the guests, whose complimentary encomiums they were de¬ 
signed to call forth. 

66. It is impossible to point out to each individual the kind 
of diet which will suit best. This, to some extent, must be a 
matter of personal observation and experience. Peculiarities of 
constitution, habits of life, age, sex, &c., require modifications 
of diet, in accordance with the natural wants of each individual. 
The aged, whose powers of life are feeble and languid, demand a 
more stimulating diet than at any other period of life, while 
children demand a generous, but plain and unstimulating diet. 
Abstinence from all that is found or suspected to be injurious, 
uniform hours, and temperate indulgence, should be observed by 
all who value lasting health more than the mere temporary gra¬ 
tification of the palate. 


APPENDIX. 


275 


THE TEETH. 

IMPORTANCE OF SOUND TEETH. 

65. Good teeth are indispensable to health, and to personal 
beauty. The matter which is continually forming and exuding 
from the cavities of decayed teeth, and passing with the air we 
breathe to the lungs, and with the food to the stomach, is an ex¬ 
ceedingly unwholesome and pernicious virus. As the process of 
decay goes on, and the cavities of the teeth enlarge, they become 
receptacles for the lodgment of particles of food which may be 
found in every stage of putrefaction, mingling with this virus, 
polluting the breath, and impairing the health. Of all the loath¬ 
some gases the physician is compelled, from his profession to in¬ 
hale, none are more offensive and loathsome than those which 
arise from the decomposition constantly going on in decayed teeth. 

DECAY OF THE TEETH. 

66. The reason why the teeth often decay so early in life, is 
usually not from any natural defect, but from the manner in which 
they are used; though impaired health during the period when 
the teeth are growing, may cause them to be imperfectly 
organized, and consequently to be less durable in structure. Im¬ 
proper and unwholesome food during the same period may have 
a similar effect, from the imperfect manner in which the body is 
nourished. It will be found by observation, that the teeth of 
children who are indulged in candies, paStry, cakes, and rich food, 
decay much younger than the teeth of those who are confined to 
an abundance of plain and wholesome food. 

67. An accumulation of foreign substances between the teeth, 
and around the roots, favors decay of the teeth, by separating 
the gums from the crown of the tooth, and thereby exposing its 
neck and roots which are unprotected by enamel. So long as the 
crown is perfectly protected by the enamel, and the neck and 
roots by the gums, the tooth cannot decay. 

68. The decay of the teeth is not caused by their natural use, 
for in those persons who chew their food principally on one side, 


276 


CLASS-BOOK OF PHYSIOLOGY. 


it will almost invariably be found, that the teeth on the opposite 
side decay first. 

69. Decay of the tooth never commences on the smooth por¬ 
tion, which is most worn by use, but in those portions where the 
food and other foreign substances are most liable to be deposited. 
The surface next to a:a adjoining tooth, the depression sometimes 
found in the top of molar teeth, and the space around the neck of 
the tooth, will prove to be the first points of decay. 

HOW TO PRESERVE THE TEETH. 

70. The great secret of preserving the teeth, is in keeping 
them clean. As long as every part of a tooth is kept clean, it 
cannot decay. 

71. To keep the teeth clean, requires care and attention. A 
soft brush is to be preferred. This is to bemused carefully and 
thoroughly, not only crosswise of the teeth, but lengthwise, and 
in all directions necessary to remove tartar, bits of food, or any 
other foreign substances. Finely pulverized charcoal, orris 
root, or myrrh, may be required occasionally, but the use of all 
acids and corrosive substances, should be carefully avoided. 

72. When decay commences, it should be arrested as soon as 
possible. The dentist should be applied to, and the cavity filled 
with gold, which will always prove to be well invested. When 
the decay has progressed so far as to be beyond the dentist’s 
skill to save the tooth, it should be immediately extracted. 

EXERCISE. 

NECESSITY OF EXERCISE. 

73. Next to air, food, and warmth, our bodies demand ex¬ 
ercise. We cannot live for any great length of time in the full 
use and enjoyment of all our faculties and powers, without a 
certain amount of strength. Strength can be secured and re¬ 
tained only by exercise. Those who attempt to live without 
exercise, gradually, though often unconsciously, lose strength till 
they become weak and frail, with little or no power of endurance. 
It is well known that animals which are constantly confined in 


APPENDIX. 


277 


stables, are not as healthy as those which are permitted to roam 
at large. Even trees which have grown in a dense forest, are not 
as strong and tough as those that have stood in the open field, 
where they have been freely exercised by the wind. 

74. We have no useless organs. Every organ has its use and 
its purpose. The muscles which constitute the great bulk of the 
body, are designed for motion. They not only serve as organs of 
locomotion to the whole body, but their use imparts activity to 
all the other organs. Muscular action causes the blood to cir¬ 
culate more thoroughly and freely through all the organs and 
tissues, and imparts increased energy to the vital changes which 
take place in the nutrition and growth of the body. 

ADVANTAGES OF EXERCISE. 

75. The advantages which arise from exercise are very ap¬ 
parent, when we contrast those who exercise with those who do 
not. Those who take a liberal amount of exercise, enjoy life 
better, and can make themselves more useful than those who are 
indolent and inactive in their habits. The man who lives an 
active, stirring life, possesses a noble form, a strong arm, a 
generous heart, and a happy frame of mind ; and enjoys life, and 
makes his friends around him comfortable and happy. Life with 
such a man is real and earnest. How different the sedentary 
man ! With him, every day brings its trials and vexations; its 
pains and its aches, neuralgia, dyspepsia, and a thousand ills that 
the active man is a stranger to, torment him, and make his ex¬ 
istence so miserable, that life itself is a burden. Instead of 
quiet, refreshing sleep, he experiences restless nights, disturbed 
by dreams and visions, still more unpleasant than the realities of 
the day ; he has no appetite for food ; no enjoyment of society; 
no comfort in any thing. 

the consequences of neglect, not always 

IMMEDIATE. 

76. The consequences of neglecting exercise, are not seen and 
felt immediately. Every person in health may be said to have in 


278 


CLASS-BOOK OF PHYSIOLOGY. 


store a certain amount of strength, or a certain capacity of en 
durance. So long as this lasts, no inconvenience will be experi 
enced, but when it becomes wasted, want and distress follow, 
and the bankrupts in health seldom regain what they have lost. 
Some mor^ susceptible or more abused organ fails to perform its 
appropriate office, or becomes diseased, and he that might have 
been healthy and vigorous, is an invalid for life, or a diseased 
man hastening to a premature grave. In one person there is a 
predisposition to lung complaints; in another, the eyes are more 
susceptible, or are more abused; and in another the stomach. 
Thus consumption, dyspepsia, weak eyes, and various other 
affections, which have little or no resemblance to each other, have 
a common origin in a neglect to use that daily exercise which is 
indispensable to permanent health. 

CHOICE OF EXERCISE. 

77. To secure the greatest benefit from exercise, it should be 
pleasant and agreeable. When taken as an unwelcome necessity, 
or as an act of penance for physical sins, or when we dislike it as wo 
do nauseating medicine, exercise can do comparatively little good. 
As a general rule, therefore, that exercise which is most agree¬ 
able, or that which interests and diverts the mind, will be found 
most useful. 

78. There should also be a variety of exercise. No one 
set of muscles should be used to the neglect of others. To 
secure symmetry and elegance of form, all the muscles must be 
called into use. If a portion only are used, they will be fully 
developed, while all the others will remain weak and small. 
Thus a student whose only exercise is walking, will secure a good 
full development of the lower limbs, while the muscles of the 
arms, back, and chest, will remain weak and small. 

79. We need recreation as well as exercise. The laborer or 
mechanic may suffer for the want of something to excite the ner¬ 
vous system, though constantly at work. Only certain muscles 
are* called into use, and they have become so familiar with the 
daily routine of labor, that the vitalizing energy of the nervous 


appendix. 


279 


system is not excited. A physician, as the author can testify 
from experience, may be literally worn out with continuous 
riding, and yet suffer extremely for want of some exercise to 
give new life and action to his system; but let him exchange 
places for a few hours each day with the mechanic, and both will 
receive decided benefit. All persons in active life require occa¬ 
sionally that variety which can be secured only by relaxation 
from accustomed labors, and recreating in a change of pursuits. 
Students, and all persons of sedentary habits, demand recreation 
as well as exercise, and are especially benefited by vacations, in 
which there is a period of exemption from study, and an entire 
change of scenes and pursuits. 

MANUAL LABOR. 

80 . Manual labor is no doubt valuable, as promoting health 
and securing muscular strength, but it does not meet all the 
wants of a majority of those who are engaged in intellectual 
labor. It fails to interest the mind and excite the nervous sys¬ 
tem. Manual-labor schools may be adapted to educate men for a 
business-life, but they have thus far failed to accomplish the 
object for which they were specially designed. With a majority 
of students, the hours allotted to work very soon become a burden, 
rather than a pleasure. Now and then, one turns from study to 
labor with pleasure and delight, and is highly benefited. 

Some are most interested in field sports, or in the various 
games of quoits, ball, wicket, &c., or in gymnastic exercises; 
others can more happily combine usefulness and pleasure in 
manual labor. Young ladies, if they choose, will find the broom 
and brush very efficient instruments of exercise. The sedentary 
of the other sex may be equally benefited by using daily the saw 
and the axe, and find sufficient pleasure in the evidences of their 
skill and power which pile up before them. Gardening, too, in 
the season of it, to those who are fond of nature, as exhibited in 
the* uprising shoot and the opening bud and flower, affords the 
means of most wholesome exercise to the body, and most inter¬ 
esting diversion to the mind. 


280 


CLASS-BOOK OF PHYSIOLOGY. 


JOURNEYING. 

81. Journeying by a private carriage is a very happy com 
bination of exercise and recreation, and should always be pre¬ 
ferred by students and literary men; but riding in railcars and 
steamboats, thought it may afford recreation, furnishes but very 
little exercise for the muscles. 

HORSEBACK-RIDING. 

82. Horseback-riding is a most efficient and elegant means 
of exercise, and is admirably adapted to promote health in all 
persons. With a spirited horse, the mind and feelings are often 
most intensely interested, and every particle of blood in the body 
receives a new impulse, and circulates with renewed activity 
through all the vessels. Each organ is jolted and jostled till a 
new life is imparted to the whole system. To one who has 
learned how to appreciate this noble animal, horseback riding is a 
most delightful mode of exercise and amusement. 

GYMNASTIC EXERCISES. 

83. Gymnastic exercises, which had their origin in the ath¬ 
letic games of ancient Greece, are remarkably adapted to the 
strengthening and growth of the muscular system. They consist 
in performing feats of strength and agility in the acts of balan¬ 
cing, climbing, leaping, running, vaulting, &c. The muscles 
acquire greater size and strength by this kind of exercise than 
by any other. 


CALISTHENICS 

84. Calisthenics is a name given to a gentler sort of gymnas¬ 
tics suited to ladies. The triangle, hoop, ball, dumb-bells, hori¬ 
zontal bar, bow and arrow, nine pins, &c., are all appropriate 
exercises for girls or young ladies, and are admirably adapted to 
produce vigorous muscles, graceful movement, and symmetry 
of form. 


APPENDIX. 


281 


85. Gymnastic or calistlienic exercises should be practised 
very moderately by the inexperienced. Persons who are unac¬ 
customed to the violent muscular effort required in some of the 
more active exercises, are very liable to produce lameness, or 
even more serious injury, by over-straining the muscles. Some 
caution is also necessary to avoid taking cold, after severe ex¬ 
ercise. It is usually better to walk a short distance, or take 
some light exercise, before sitting down. 

WALKING. 

86. Walking is, perhaps, of all other exercises, the most to be 
commended. When practised as it should be, at the rate of from 
four to five miles an hour, walking brings into exercise a large 
number of muscles, affords a constant variety of objects to interest 
and divert the mind, and offers the greatest facilities for obser¬ 
vation—it is always available, and has the virtue of costing 
nothing. Walking, to accomplish its full purpose, should be a 
free, unrestrained exertion of the powers of locomotion, and 
should have an object in view. In walking, the form should be 
erect, the arms and chest should be unrestrained, and allowed 
that free use which nature designed them to enjoy, and every part 
of the dress should be loose and easy. 

COLLECTING SPECIMENS. 

87. Collecting specimens of natural history is admirably 
adapted to interest the young, and afford an object for walking 
that is both exciting and ennobling. Plants, insects, birds, 
minerals, and shells, when we are once initiated into their beau¬ 
ties, are highly interesting objects of investigation and thought, 
and no pursuit is better adapted to expand and exalt the powers 
of the mind than the study of nature, as seen in the forest, in 
the open field, in the quarry, or on the beach. 

TIME FOR EXERCISE. 

88. The begt time for exercise and recreation is in the morn¬ 
ing or early part of the day, when the air is pure and invigorat- 


282 


CLASS-BOOK OF PHYSIOLOGY. 


ing, and the powers of the body not exhausted by fatigue or ex* 
citement. The morning is also the best time for study 5 and 
many students indulge in the feeling, that the early part of the 
day is too valuable to be lost in exercise; therefore they wholly 
neglect morning exercise, or defer it till the mind has become 
fatigued, and the nervous system so far exhausted as to impart 
but little energy to the muscles. Under such circumstances, 
exercise very soon becomes a drudgery, and fails to impart 
health and vigor to the system. Exercise immediately before 
meals, to the extent of inducing fatigue, instead of improving 
the appetite, exhausts the nervous energy, and unfits the diges¬ 
tive organs for the reception of food. The most appropriate 
hours for students are soon after breakfast, and an hour or two 
before twilight. Invalids should avoid the dampness of the 
early morning and evening, and in summer the heat of mid-day, 
and select that portion of the day at each particular season of 
the year when the temperature will be the mildest and the most 
agreeable. In the early spring, the afternoon, though regarded 
as the most pleasant, is often the most objectionable part of the 
day, from the fact that the air is saturated with vapor, and the 
liability to contract colds is greatly increased thereby. 

USE OF THE EYES. 

89. The organ of vision is more delicately constructed, and 
contributes more to our happiness than any other organ of the 
senses. It is equally true that the eyes are more abused than 
any other organ. 

90. The eye is formed for the special purpose of receiving 
and transmitting to the brain impressions of the form, size, and 
color of the various objects with which we are surrounded. It 
is adapted to viewing objects at a distance as well as to minute 
inspection of those objects which may be brought near. But 
long-continued inspection of small objects, however near, is 
always at the risk of fatiguing this organ, and there is probably 
nj organ of the body which oftener suffers for want of rest 
than this. 


appendix. 


283 


ARTIFICIAL LIGHT. 

91. Artificial light, as produced by caudles, oil, burning 
fluid, or gas, is more liable to injure the eyes than the natural 
light of the sun. It is well known that the properties of natural 
and artifical light are not the same. 

92. Artificial light, however produced, is deficient in the 
green and blue rays which are most congenial to the eye, and 
abound in yellow and red rays, which are most unwelcome colors 
to the eye. ^ It has been found by experience that the eyes are 
more liable to be injured by artificial light in the morning than 
in the evening. Very few persons have ever persisted in the 
habit of early morning study without ultimately injuring the 
eyes. 

93. In using an artificial light, it is of great importance that 
»the position should be such that the light does not shine directly 
into the eyes, for the direct rays are much morerirritating than 
those which are reflected from the objects on which the eyes rest. 
The back may be turned to the light, or the light may be placed 
high enough to have its rays fall on the eyelids, or the eyes may 
be protected by a screen. 


TWILIGHT. 

94. The eyes are often injured by using them at twilight. 
The transition from daylight to dark is usually so gradual, that 
in studying or reading at this hour the light becomes insufficient 
before we are aware of it, and the eyes are strained and perma¬ 
nently injured in an attempt to see without a proper amount of 
light. 

95 . The eyes should always be permitted a short season of 
rest from daylight to dark or to artificial light, because the eyes 
require a little time to accommodate themselves to the change of 
light, just as in passing from open daylight into a dark room, we 
can scarcely distinguish a single object at first; but if we wait 
till the eyes have accommodated themselves to the change, we 
can see very well; but when we return to the light again, it is 


284 


CLASS-BOOK OF PHYSIOLOGY. 


nearly as difficult to distinguish objects as before. In either 
case, the transition is more or less painful, and would prove 
highly injurious if often repeated. 

WEAK EYES. 

96. Weak eyes are a great affliction, and they are the most 
difficult of all the organs to restore to health. It is, therefore, 
of the highest importance that any weakness or symptoms of 
disease of the eyes should receive immediate attention. As soon j 
as there are any indications of disease of the eye, it should enjoy 
perfect rest till it is fully restored. Any attempt to read, study, ' 
or apply the eye, is absolutely certain to increase the difficulty. 
The use of the eyes by artificial light should be avoided till they 
are perfectly well and strong. The author has known repeated 
instances in which a return of disease has been produced by 
reading in the evening. 

RULES FOR USING THE EYES. 

97. 1st. Avoid long application to minute objects, and rest 
whenever the eyes begin to smart or ache. 

98. 2d. Use the daylight, and avoid a long continued use of 
artificial light. 

99. 3d. Let the eyes rest during twilight. 

100. 4th. In studying or reading, do not allow the light to 
shine directly into the eyes. 

101. 5 th. When the eyes become weak, give them rest. 

BATHING. 

ANTIQUITY OF BATHING. 

102. The practice of bathing is of great antiquity, and has 
been resorted to in every stage of society for the purposes of clean¬ 
liness and health, or as a recreation and luxury. The ancient 
Hebrews, Greeks, and Romans all practised ablutions. Among 
the Persians, Arabs and Hindoos, baths were employed as a 
means of cleanliness and recreation at a very early period. The 
bathing establishments of the Romans were'constructed with sur- 



APPENDIX. 


285 


passing elegance and splendor, and at an immense cost to the public 
treasury. When they were in their highest perfection, it is supposed 
that eighteen thousand persons might have been bathing at once, 
and been provided with all the varieties of the cold, hot, tepid and 
vapor baths. When Alexandria was plundered in 640, there were no 
less than four thousand public baths, which were supposed to have 
been constructed in imitation of those at Rome. At the present 
day, the vapor-bath in Russia is general, from the emperor to the 
lowest serf; and there is hardly a hut in all the dominions of the 
autocrat that is so destitute as not to possess its family vapor-bath* 
In Turkey, Egypt and Persia, the habit of resorting to the bath as 
a luxury is general, from the pacha down to the poor camel-driver. 
In fact, all the nations of Continental Europe and many of the un¬ 
civilized tribes of Asia, greatly excel the otherwise more refined 
English and Americans in their establishments for securing per¬ 
sonal cleanliness. As a people, it must be confessed, that the 
Americans are proverbial for their neglect of personal cleanliness. 
Most of our cities have no public establishments for bathing, 
adequate to meet the wants of the masses ; and a great majority 
of our public houses, though amply provided with every thing else 
desirable, are wholly destitute of means for furnishing their guests 
with the convenience and luxury of a bath. Still, it cannot be de¬ 
nied that the utility of bathing, as a means of promoting health, 
has been most abundantly established by various nations in all ages 
of the world, and in every variety of climate; and it may well be 
asked, why should the people of the United States deprive them¬ 
selves of a luxury so highly conducive to health and happiness ? 

ADVANTAGES OF BATHING. 

103. Habits of uncleanliness are not unfrequently the incip¬ 
ient cause of serious disease of the vital organs. The natural 
excretions, together with the exfoliations of the scarf-skin, form 
a coating of foreign matter over the entire surface of the skin, 
and effectually close up its pores and obstruct its appropriate 
functions. This thin pellicle of animal impurities not only con¬ 
fines within the system substances which are actually poisonous, 




286 


CLASS-BOOK OF PHYSIOLOGY. 


but becomes itself the seat of detention of foreign impurities ; 
which here find a resting-place till they are absorbed into the 
system. 

104. Ablution is therefore a necessity—not a mere luxury, 
which may be indulged in or omitted at pleasure. Persons may 
occasionally live in total neglect of this, as of other means of pro- ; 
mo ting health, and yet escape disease for a time ; but an impure j 
skin will, in the end, be found incompatible with uniform and 
lasting health. 

105. Aside from the absolute necessity of water as a purifier ; 
of the skin, all persons esteem it as grateful and refreshing when 
applied to the hands and face, and, in these accustomed to its 
use, it is equally refreshing to the whole body. The oriental cus¬ 
tom of offering water for washing, as the first act of hospitality 
to the weary traveller, is worthy of our admiration. Even food 
to the hungry is scarcely more refreshing than the bathing of the 
wearied limbs with water. When applied to the skin, it produces 
an instantaneous contraction of the capillary vessels, forcing out 
their contents, and admitting a new supply of blood. An im¬ 
pulse is thus given to the whole circulation, while new tone and 
vigor is imparted to the capillary and nervous systems. Water 
to the skin is thus one of the best of tonics. It relieves inter¬ 
nal congestion, calms mental excitement, quiets nervous irritabil¬ 
ity, carries off feverish heat when it exists, and equalizes the cir¬ 
culation. 

106. When we consider the uses of water to the person 
alone, it is not strange that, in an age 11 when man drew his lux¬ 
uries more from nature and less from works of his own—when 
water was his friend more than his servant—water was regarded 
as a representation of the Deity, and was raised to the dignity 
of a mythological god. Thus the rivers of Greece and Rome 
were represented allegorically by a tutelar god with his attend¬ 
ant nymphs, and to this day the Ganges is adored by the votaries 
of Brahma. Baths were dedicated by the ancients to the divin¬ 
ities of medicine, strength, and wisdom—namely, iEsculapius 
Hercules, and Minerva, to whom might properly be added the 




APPENDIX. 


287 


goddess of health, Hygeia. The use of water has been adopted 
as one of the symbols of Christianity.” 

DIFFERENT KINDS OF BATHS. 

107. Water is applied to the shin in a variety of ways, ac¬ 
cording to the fancy and convenience of each individual, and ac¬ 
cording to the purpose to be accomplished by its use—by immer¬ 
sion, a plunge, a douche, or a shower. The most simple and 
natural division of baths, in regard to temperature, is into cold, 

, warm, and hot. These terms, so far as our sensations are con¬ 
cerned, are merely relative^ and cannot be fixed uniformly at the 
same temperature. 

108. Water of eighty degrees would produce a sensation of 
pleasant and agreeable warmth to the hand immediately after expo¬ 
sure to a lower temperature; but if applied to the body at the same 

i temperature, it would produce a decided impression of cold. We 
can therefore assign only certain general limits to each kind of a 
I bath. A full bath, under eighty-four degrees would be regarded 
as cold by most persons; from eighty-four to ninety-two, tepid; 
from ninety-two to ninety-eight, warm. Most persons, under ordi¬ 
nary circumstances, will assent to the following divisions—namely; 
for the cold bath, under eighty-four; for the tepid, from eighty- 
i four to ninety-two ; for the warm bath, from ninety-two to ninet} T - 
eight; and for the hot bath, any temperature over ninety-eight 
degrees. A medium temperature for the tepid bath will then be 
eighty-eight, and for the warm ninety-five degrees. 

flOLD BATH. 

109. The cold bath is usually taken at about the same tem¬ 
perature as the air of the apartment, and may be applied either 
by a plunge^ a douche , or with a sponge. 

PLUNGE BATH. 

110. The plunge bath is very agreeable in a warm apart¬ 
ment or in the open stream in warm weather, and affords a high- 



288 


CLASS-BOOK OF PHYSIOLOGY. 


ly useful means of cleanliness, recreation and exercise, when ao- 
companied with swimming, or when followed by liberal friction. 
Swimming for most persons, is a very agreeable and active exer¬ 
cise, and a valuable accomplishment for all. In the act of swim¬ 
ming, the respiration is accelerated, and nearly all the muscles of 
the body are brought into active exercise, and the capacity to 
evolve animal heat greatly increased. Persons who swim or take 
active exercise in the bath, resist the operations of the cold, and 
experience a salutary reaction and glow, much better than those 
who are inactive. 


THE DOUCHE. 

111. The douche, which consists in pouring a large stream 
of water on the whole person, or on a particular part, is useful 
mainly when it is desirable to gain a decided shock, and is 
usually applied only to a particular part. 

SHOWER-BATH. 

112. The shower-bath admits of considerable variety, both 
in its application and its effects. It may be applied gently in 
small streams, or with great force and in large streams. Many 
of the portable shower-baths, as offered in the shops, contain 
large apertures, which allow the water to fall in torrents, and 
few persons have the courage or ability to endure the force, it 
being more like a hail-storm than a gentle, refreshing shower. 
The shower-bath should be so constructed that the streams shall 
be small, and easily controlled at the pleasure of the bather. 
When properly conducted, we can testify from our own experi¬ 
ence that the shower-bath is a most delightful means of promoting 
health. It gives a general shock to the whole system, and is 
followed by a grateful glow of warmth and a general activity of 
the circulation. For those who can bear it, the shower-bath is 
to be preferred to all other forms of cold bathing. The quantity 
and force of the water should be under the control of the bather, 
and the apartment should be so arranged that the whole, or only 
a part of the person should be exposed at pleasure. The sponge- 









appendix. 


289 


bath is to be recommended for its convenience and universal 
presence. It can always be enjoyed at home and abroad, and 
when faithfully applied it is a highly salutary and agreeable bath. 

EFFECTS OF COLD BATHING. 

113. On the application of cold water to the surface of the 
body, by either of the above methods, the skin immediately 
shrinks, and the whole of the tissues contract, diminishing the 
diameter of the cutaneous vessels and their capacity for blood. 
A portion of the blood circulating near the surface is thus sud¬ 
denly thrown in on the deeper parts, and especially on the in¬ 
ternal organs. This sudden change in the order of things 
stimulates the nervous system, and thus rouses the heart to more 
energetic action to relieve the internal organs by sending back 
the blood to the surface. As the warm blood comes rushing 
back to the surface, a general glow of warmth is experienced 
throughout the whole system. There is a general redness of the 
surface, the mental faculties are clear and strong, the senses are 
acutely alive to all external impressions, the appetite is sharpened, 
and the whole organism invigorated. This highly desirable 
state is what is called a healthy reaction. When this does not 
take place, the surface becomes cold and bloodless, the heart and 
circulation languid, and the mental faculties dull and depressed. 
Under such circumstances, the associations connected with the 
bath are disagreeable and forbidding. With a proper reaction, 
nothing can be more refreshing and grateful to the feelings than 
a generous bath. Without it, nothing is more unwelcome or 
more to be dreaded. In one case, the cold bath is a highly use¬ 
ful means of promoting health; and in the other, it is as de¬ 
cidedly pernicious. The aged, the invalid, and the bloodless, 
who have not sufficient vigor to secure a healthy reaction, cannot 
resort to the cold bath with impunity. But with the opposite 
and more fortunate class, it is not only a luxury, but a most 
valuable means of invigorating the health and strengthening the 
constitution to bear with impunity exposure to cold and sudden 
changes of temperature. For the most part, those persons who 
21 




290 


CLASS-BOOK OF PHYSIOLOGY. 


practise daily ablution in cold '■water, are but seldom subject to 
colds and fevers, and when they are, they recover much sooner 
than others. The ability to practise cold bathing is in part the 
result of training. The bather at first uses tepid water, and 
gradually becomes accustomed to a lower temperature, till the 
cold bath comes to be preferred to any other. The uninitiated 
should therefore commence with water at an agreeable tempera¬ 
ture, and gradually diminish it till they can bear the water at the 
same temperature as the surrounding air. 

TEPID BATH. 

114. In the tepid bath, the shock is milder than in the cold, 
and the reaction less marked. It is therefore to be preferred by 
those who have not sufficient vigor to endure cold bathing. The 
precise temperature of the tepid bath may be regulated according 
to the feelings of the patient. 

TIME FOR COLD BATH. 

115. The best time for the cold or tepid bath is early in the 
morning or about an hour before dinner. Persons in health will 
usually prefer the bath immediately after rising in the morning, 
since it occupies less time than at any other hour. Invalids and 
persons of leisure will find the bath more agreeable three or four 
hours after breakfast. Bathing immediately after taking a full 
meal interferes with the process of digestion, and has a tendency 
to divert a portion of the nervous energy from this process, 
while the nervous and vascular excitement which constitutes a 
healthy reaction, is less perfect than where digestion is com- „ 
pleted. The capacity for a healthy reaction is also diminished 

by mental or bodily fatigue, to an extent that renders the cold 
bath wholly unsafe after the body has become weary by labor, or 
the nervous system depressed by mental effort. Mental excite¬ 
ment, an evening debauch, and unusual fatigue, are circumstances 
which render the cold bath improper on the following morning, 
even though the individual may have been in the habit of using 
it daily. When the circulation is languid and the skin cool, or 



APPENDIX. 


291 


when there is any unusual depression of the vital energies, the 
cold bath ought to be postponed. 

DURATION OF COLD BATH. 

116. The duration of the cold bath should not be over ten 
minutes, unless it is accompanied by swimming or active exer¬ 
cise, when it may be continued as long as it is found to be 
pleasant and agreeable. Invalids and persons whose capacity 
for reaction is feeble, should not spend more than two or three 
minutes in the bath, and they should then be enveloped in a 
warm blanket, or speedily dressed in warm clothing. 


WARM BATH. 


117. The warm bath has a soothing, tranquillizing effect on 
the whole system. It quiets the circulation and calms all nervous 
excitement, by equalizing the circulating fluids and producing a 
general equilibrium. The bather experiences a most delightful 
consciousness of comfort and well-being, and an inclination to 
repose, without any feeling of inability for mental or bodily ex¬ 
ercise. The warm bath is specially grateful to the weary and 
fatigued, and is an efficient means for the relief of internal in¬ 
flammations, congestions, fevers, and colds. For children that 
are nervous and irritable, from teething or other causes, the 
warm bath is one of the best anodynes that can be administered. 
It diminishes the animal heat, calms the nervous excitement, and 
disposes to quiet, refreshing sleep. The hot bath acts as a 
stimulant, communicating heat to the body, increasing the heart’s 
action, and producing a high degree of nervous excitement. If 
it be continued for any great length of time, it is followed by a 
feeling of prostration, amounting to fainting, and even apoplexy, 
when the bath is indulged too long. The hot bath is useful 
chiefly when a decided impression on the circulation and the 
nervous system is desired. 



292 


CLASS-BOOK OF PHYSIOLOGY. 


VAPOR BATH. 

118. The vapor bath does not differ essentially from tha 
■warm bath in its physiological effects. It stimulates the cuta¬ 
neous circulation, determines the blood to the surface, and causes 
an increased activity of the functions of the skin. When the 
skin is dry and harsh, the vapor-bath is to be preferred to all 
others, since it softens the cuticle, and produces exfoliation more 
perfectly than any other. It is a very valuable means for the 
relief of colds and inflammations, and is a great luxury to the 
weary and fatigued. It equalizes the circulation, and is highly 
refreshing and invigorating. From the increased activity it im¬ 
parts to the cutaneous vessels, immediate exposure after its use 
is less liable to be followed by colds than after the warm bath 
by immersion. 

TRANSITION BATH. 

119. Transition baths are those in which there is a quick 
passage from a warm or hot to a cold medium, whether vapor or 
water. In the Russian bath, the bather enters a warm room, 
filled with vapor produced by pouring water over red-hot stones, 
and remains till the body is in a profuse perspiration, and then 
rushes forth to roll in the snow or plunge into the nearest stream. 
When neither is accessible, he cools himself by affusions of cold 
water, pouring over his head a bucketful at a time. The heat 
of the bath is seldom less than one hundred and twenty degrees 
Fahrenheit, and is often as high as one hundred and forty. 
The transition baths of the ancient Romans must have been 
nearly the same in effect as the Russians of the present day. 
These abrupt transitions of temperature may seem almost in 
credible to those who have fallen into the error of supposing that 
the liability to contract colds is increased by the warm bath. 
The fact, however, is, that the power of resisting cold becomes 
greater in proportion as the animal heat is above the natural 
standard. After exposure to the intense heat of the high tem¬ 
perature of the Russian bath, there is a state of nervous and vas¬ 
cular excitement and a degree of animal heat which enables the 


APPENDIX. 


293 


bather to bear with impunity the sudden application of cold, and 
part with an amount of heat which, under other circumstances, 
could not fail to be injurious. When the application of cold is 
carried just far enough to reduce the animal heat to a medium 
temperature, the effect on the system is most salutary and de¬ 
lightful. The previous excitement is now followed by a most 
grateful calm, the pulse is restored to the equilibrium of health, 
the mind is clear and active, and every part of the body refreshed 
and invigorated. As a relief to a cold, or the premonitory symp¬ 
toms of a fever, the efficacy of the warm bath is unquestionably 
increased by a sponge, a shower, or a douche. Under any cir¬ 
cumstances, most persons will find the warm bath more agreeable 
and more useful, when the excitement and the animal heat de¬ 
rived from the bath are relieved by the application of cold water; 
though it is very doubtful whether the high temperature of the 
Russian bath is not exhausting to the system, if often repeated, 
notwithstanding the transition to the cold bath so soon restores 
the equilibrium of animal heat. But a bath at about blood-heat, 
followed by a cold showering or sponging, is free from this ob¬ 
jection ; and while it is certainly very grateful to the feelings, 
it is also highly salutary as a means of promoting health, as the 
author can testify from personal experience. 

TIME OF DURATION OF WARM BAT II. 

120. The warm or vapor bath may be taken at almost any 
hour of the day, except after a full meal, though the hour before 
retiring to bed is usually preferred, on account of there being 
less subsequent exposure at that hour than at any other. A 
much longer time may be spent in the warm bath than in the 
cold—from fifteen to thirty or even forty minutes, according to 
the feelings and constitution of the individual. 

REPETITION OF BATHING. 

121. The frequency of bathing is to be determined by the 
age, constitution, and habits of life of the individual. The 
ao-ed, in whom the vital functions are less active, and the vital 

O' 


294 


CLASS-BOOK OF PHYSIOLOGY. 


powers less vigorous, will find two or three times a week often 
enough to resort to the bath for the purposes of health. Chil¬ 
dren should be bathed daily, the first year with warm, during the 
second with tepid, and subsequently with cold water. The prac¬ 
tice of bathing infants in cold water is attended with very great 
risk. Children that are remarkably protected by flesh, or who 
have inherited hardy constitutions, may endure the exposure with 
impunity; but for the slender and feeble it will, in a majority 
of cases, prove decidedly pernicious, if not fatal to life. For the 
purposes of health and cleanliness, the warm bath need not be 
resorted to oftener than two or three times a-week by adults. 
Persons in full health ought to practise bathing every morning 
on rising from the bed, as part of the duties of the toilet. Daily 
ablution contributes not only to personal comfort, but it is a most 
salutary means of fortifying the system against colds, fevers, and 
many diseases to which we are otherwise exposed. There is a 
very close sympathy between the skin and the nervous membrane 
of the alimentary canal; and those who preserve the skin in a 
clean, healthy and vigorous condition, will find themselves abun¬ 
dantly rewarded by exemption from many gastric and intestinal 
complaints to which others are iiable. 

CLOTHING. 

122. Dress does not make the man, but it is often indicative 
of his character. Some men dress in such a manner as to indi¬ 
cate that they estimate themselves by the cost per yard of the 
garments they wear. Others dress so as to convey an impres¬ 
sion of perfect indifference to the feelings and sentiments of those 
around them. Both are wrong. Our personal appearance, which 
depends to a great extent on dress, is a matter of some conse¬ 
quence—and the man who wholly disregards the customs and 
habits of others, in this respect, will be very likely to be indif¬ 
ferent to the sentiments and feelings of society in other particu¬ 
lars, and at least may be in danger of passing for less than his 
true worth. But the fop, whose only accomplishment is the 
dress he wears, is usually despised as thoughtless and vain. 


APPENDIX. 


295 


123. The style of dress which is most to be commended, is 
that which will not attract attention either for its gaudiness or 
its plainness. The external appearance of our clothing should 
always be regarded less important than its practical uses, inas¬ 
much as bodily health is infinitely more important than personal 
appearance. 

SUMMER CLOTHING. 

124. During the warm season we require clothing which will 
protect the body without retaining too large an amount of heat. 
For this purpose, we prefer in summer materials which are good 
conductors of heat. Linen is a good conductor of heat, and 
therefore furnishes the most agreeable material for extreme 
warm weather. Cotton and worsted, though not as- good con¬ 
ductors as linen, are usually found sufficiently cool for the tem¬ 
perature of the northern States, where the climate is so changea¬ 
ble that there are but few days in the season when linen can be 
worn with safety. 

WINTER CLOTHING. 

125. Winter clothing should correspond somewhat with the 
exposure both in quality and amount. The object to be sought 
in winter clothing is, not to produce heat, but to retain the heat 
which the body is constantly evolving. If a dead man were en¬ 
veloped in ever sc many clothes, he - would not become warm 
thereby—though he might retain for a longer period the warmth 
he already possessed. Those materials which are the poorest 
conductors of heat will retain the heat of the body longest, and 
are therefore to be preferred. 

126. Woollen is one of our best non-conductors of heat, and 
all garments formed from this material are regarded as warm 
clothing. Silk is not as good a non-conductor as woollen, though 
better than cotton. All kinds of furs are good non-conductors, 
but they are liable to two very serious objections: 1st. Furs are 
too warm for ordinary exposure, and cause too great a change of 
temperature when they are removed. 2d. Fur garments are ob- 
iectionable because they prevent the escape of the perspiration, 


296 


CLASS-BOOK OF PHYSIOLOGY. 


and confine it within the garments usually worn inside of the fur. 
Both these circumstances tend to render those who wear furs 
more liable to colds than those who wear only woollen or silken 
garments. 


AMOUNT OF CLOTHING. 

127. The amount of clothing should depend on the constitu¬ 
tional vigor and the exposure of each individual. 

128. The greatest amount of clothing is required in infancy 
and old age. The power of resisting cold is less in those ex¬ 
tremes of life than during any of the intervening periods of life. 
Invalids and persons of sedentary habits require warmer clothing 
than the vigorous and active. 

129. The amount of clothing should also depend in part on 
the exposure. In-doors we require less than during an out-dooi 
exposure,—less when taking active exercise than when inactive. 
We suffer more during the winter months from the frequent 
changes of temperature than from the long continuance of cold. 
The amount of clothing, therefore, should be sufficient to insure 
a constant and uniform protection against sudden changes. And 
it is better to wear more clothing than we absolutely require, 
when the weather is mild and pleasant, than to be unguardedly 
exposed to cold. 

130. Those who are accustomed to spend most of their time 
in-doors should put on extra garments for out-door exposure, 
except when walking or taking active exercise. The habit of 
“ bundling up” as it is called, with an unnecessary amount of 
clothing, is injurious for two reasons. It produces too much 
warmth, and prevents that healthy reaction on exposure which 
is conducive to vigorous health. It is especially injurious to 
bundle up the face and nock with fur collars and shawls, which 
are so warm that colds will be contracted when they are removed. 

. UNDER GARMENTS. 

131. Most physicians recommend, in a changeable climate, 
the constant wearing of flannel or silken under garments next to 


APPENDIX. 


297 


the skin. They absorb the perspiration, and preserve a uniform 
temperature of the surface of the body, and prevent that sense 
of chilliness which we are very liable to experience without flan¬ 
nels. During summer, however, these garments may be thinner 
than in winter. 

FORM AND SIZE OF GARMENTS. 

132. The form and size of our garments is a matter of some 
importance, since the human form is of infinitely more conse¬ 
quence than the garment which is designed to cover and protect 
it. All the garments of both sexes should be made free and 
easy, and not “ snug fits.” Garments that are loose may be 
graceful and becoming, as well as better adapted to the full and 
perfect development of the form. Tight garments compress the 
vital organs, interfere with free muscular exercise, confine the 
perspiration, and are not so warm as those which permit a space 
of air between the body and the clothes, as any one can testify 
who has made the experiment of wearing tight boots on a cold 
day. 

FASHION OF GARMENTS. 

133. The folly of following fashions in dress is at no period 
more marked by its legitimate results, than in the practice too 
common among Americans, of dressing infants and small chil¬ 
dren with the neck and arms bare and unprotected. The fearful 
mortality among children in our cities during the winter months, 
is abundant proof that cold annually sends a large number to an 
early grave. That the susceptibility to cold must be much 
greater when a considerable portion of the body is entirely 
naked, is very evident. If we regard anatomical structure, 
there is no portion of the body that might not be unclothed with 
equal propriety. In the arms all the principal blood-vessels are 
near the surface, and have no natural protection against the cold, 
as in the face, where the vessels are small and deep-seated. It 
is well known that we usually experience the effects of cold in 
the extremities first, and that, in riding, men seldom suffer from 
cold so long as the hands and feet are kept warm. 

13* 


298 CLASS-BOOK OF PHYSIOLOGY. 

134. If we lose sight of the anatomical limits of the neck, 
and describe it as extending from the head to the top of a fash¬ 
ionable dress, the reasons for its protection will be very obvious, 
when we consider, that in this space are located the larynx, tra¬ 
chea, bronchial tubes and the upper portion of the lungs, organs 
on which croup, bronchitis, and lung fever—which constitute a 
very large share of the diseases of winter—have their location, 
and are caused in thousands of instances by want of proper 
clothing. A blind devotion to fashion among children and 
females thus often proves a most reckless sacrifice of health and 
life. 


BLEEDING. 

135. Bleeding may take place as the result of an injury, or it 
may occur spontaneously from some one of the internal organs. 

136. In case of an injury, it is important to consider whether 
the bleeding is from an artery or a vein. If the bleeding is from 
an artery, it may be known by the bright scarlet color of the 
blood, and from its issuing in jets. When the bleeding is from 
a vein, it is a dark purple color, and flows continuously. The 
bleeding from a vein may be very profuse at first, and soon sub¬ 
side of its own accord. Arterial bleeding is more liable to con¬ 
tinue till it is arrested by artificial means. 

137. To stop arterial bleeding, a surgeon will usually be re¬ 
quired to take up and tie the divided artery. In the absence of 
a surgeon, the bleeding may be arrested by putting the finger in 
the wound and pressing on the bleeding aperture. If the bleed¬ 
ing is from either of the extremities, you may find the position 
of the artery above the injury, and press on it with your thumb 
or finger till the bleeding is controlled, or you may fold a piece 
of rag several times, and placing it over the artery, tie a hand¬ 
kerchief twice around the limb, and the compress thus made, 
and twist the handkerchief with a stick, till the pressure is suf¬ 
ficient to produce the desired result. In bleeding from a vein, 
a small fold of cloth, bound firmly upon the wound, will usually 
be found sufficient. 



QUESTIONS TO APPENDIX. 


THE AIR WE BREATHE. 

1. What is the height of the air around the earth 7 What is its 
pressure on every square inch of the earth’s surface 7 2. What are 
the constituents of the air 7 3. What is oxygen 7 When it combines 
rapidly with any substance, what does it produce 7 4. What effect does 
it have on animals to breathe pure oxygen 7 How is man dependent 
on oxygen 7 How does it affect the blood 7 5. How does oxygen 
affect the respiration and circulation 7 

6. For what is nitrogen useful 7 Does it support combustion or 
animal life 7 Why not 7 

7. What is carbonic acid 7 8. What are the effects of breathing 
one per cent, of carbonic acid 7—three or four 7—six or seven 7 ten 7 
How are persons affected who confine themselves in apartments con¬ 
taining only a small excess of carbonic acid 7 How does it increase 
the liability to consumption 7 9. How is carbonic acid formed 7 What 
per cent, of the respired air is carbonic acid 7 How much per day 7 
10. How much carbonic acid escapes from the skin daily 7 What re¬ 
markable fact 7 11. How much watery vapor is the respired air found 
to contain 7 Is this vapor pure water 7 What causes the fetid odor 
in the breath of some persons 7 What increases this odor 7 

12. What is said of the natural excretions of the skin 7—of the 
amount of impurities which pass off from it 7 What is a general es¬ 
timate of the amount of the daily excretions of an adult 7 What are 
the excretions composed of 7 What causes the peculiar odor of per¬ 
spiration 7 13. Give the total quantity of impurities which are daily 
given off by an adult. According to Dr. Lee, how much air does 
each person render unfit for respiration every minute 7 


300 


CLASS-BOOK OF PHYSIOLOGY. 


VENTILATION. 

14. What is said of ignorance in regard to ventilation ? 15. What 
is the effect of breathing impure air ? What is the condition of air 
which has been breathed over and over again in our parlors, school¬ 
rooms, &c. ? 16. What is a common cause of typhus fever ? Where 
do typhus fever, dysentery and the cholera take their origin ? What 
is indicated by the countenance in the spring ? 

17. What heating apparatus was used till within the last half cen¬ 
tury? What is said of it? 18. What is said of an open fire as a 
ventilator ? What objection to an open fire ? 19. How does an open 

fire compare with an airtight stove? 20. What is said of hot-air fur¬ 
naces and ventilating stoves ? Is this system of heating perfect ? Why 
not ? 21. What is the temperature of air as it is delivered from most 
hot-air furnaces ? How may this objection be obviated ? 22. What 
method of ventilation is the best? 23. Repeat the rules for ven¬ 
tilation. 

DIET. 

30. How does man differ from other animals in regard to diet ? 
How are other animals directed in the selection of food ? How is 
man endowed ? How should he select his food ? 31. What circum¬ 
stances should influence the choice of food ? 32. How do the con¬ 
stituent elements of the body vary at different periods of life ? What 
predominates in middle life ?—in the child ? What is the condition in 
the aged? 

33. What dissimilarity exists in different individuals of the same 
age ? To what should each person adapt his diet ? 34. What do the 
inhabitants of cold climates require ? On what do the inhabitants of 
tropical climates subsist ? 35. What modification of food is required 
in temperate climates ? What would be the effect of indulging in 
summer in a diet which might be appropriate in winter? What 
should each person possess ? 36. In what proportion are different 
substances nutritious ? From what source do animals derive the ele¬ 
ments of their growth ? On what does the nutritive value of differ¬ 
ent substances depend ? 

37. What is said of milk ? 38. What elements does milk contain ? 
39. What is said of fish ?—of salmon and eels, and of haddock, sole, 
flounder, cod and turbot ? 40. How is the digestibility offish diminish¬ 
ed ? When may a fish diet be employed i At what season of the year 


QUESTIONS TO APPENDIX. 


301 


is fish best adapted to the wants of the body ? 41. What is said of 
oysters ? 42. When are fish and oysters unsafe articles of diet ? 
43. What is said of lobsters ? 

44. What is said of meat ? 45. Which are most digestible, young 
meats or old ? 46. How does the vegetable kingdom compare with 
the animal in the number and variety of its aliments ? What are the 
nutritive principles in vegetables ? 47. What essential elements are 
to be found in abundance in vegetables ? What examples of animals 
that live exclusively on animal—and on vegetable food ? What varia¬ 
tion in the digestive organs of the two classes? What is man in 
structure and habits ? 48. What instances are given of an exclusive 
diet of each ? 49. What is the universal preference if mankind ? 

50. What is said of ripe fruits ? How are they regarded by most 
city physicians ? Under what circumstances are fruits dangerous ? 
Of what are the injurious results the consequence ? 51. Under what 
circumstances may fruit and vegetables be regarded as safe ? How 
are children affected by fruit ? What caution should children ob¬ 
serve ? What is said of orange-peel, and the skins and stones of 
cherries, plums and grapes ?—of cucumbers, beets, green potatoes, and 
green fruit ? 

52. Of what importance is water ? What per cent, of the blood is 
■water ? What portion of the whole body is water ? What purposes 
does water accomplish in the human body ? 53. How does water 

compare with other drinks ? 54. Has nature offered any substitute 

for water ? 55. What is the effect of water on fires ? 

56. What substances are naturally difficult of digestion ? What 
circumstances render the digestive process more easy ? How does the 
flesh of young animals compare with others in digestibility ? What 
circumstance facilitates digestion ? 57. How does the art of cooking 
affect the digestibility of food ? 58. What is said of boiling ?—59. of 
roasting? 60. of frying? 61. of pastry?—of different articles com¬ 
pounded together ? 63. How does the rapidity of digestion vary ac¬ 
cording to Dr. Beaumont ? 64. What is said of variety of food ? 65. 

Is a great variety at the same meal beneficial 1 66. How is the diet 
of each individual to be determined ? 

THE TEETH. 

65*. To what are good teeth indispensable ? What is said of the mat¬ 
ter which is constantly exuding from decayed teeth ? Whats ubstances 
collect in the cavities of decayed teeth ? 66*. Why do the teeth often 


302 CLASS-BOOK OF PHYSIOLOGY. 

• 

decay so early ? 67. How does an accumulation of foreign substances 

between and around the teeth cause decay? 68. Does the natural use 
of the teeth cause their decay ? 69. Where does decay usually com¬ 
mence ? 70. What is the secret of preserving the teeth ? 71. How 
may the teeth be kept clean ? 72. What should be done when decay 
commences ? 


EXERCISE. 

73. What is said of \he importance of exercise?—of strength? 
What is ultimately the condition of those who live without exercise ? 
74. For what are the muscles designed? How does muscular action 
affect the blood, and the vital changes which take place in the growth 
and nutrition of the body ? 75. What are the advantages which arise 
from exercise ? 76. Why are the consequences of neglecting exercise 
not seen and felt immediately ? What organ is most likely to become 
diseased first ? 77. How can we secure the greatest benefit from ex¬ 
ercise? What exercise will be found most useful ? 78. Why should 
there be a variety of exercise ? What will be the condition of the 
muscles that are not exercised? 79. What do we need besides exer¬ 
cise ? How may the laborer or mechanic suffer ?—How may the 
physician suffer ? What do all persons require ? 80. What is said 
. of manual labor?—of field sports, games, &c. ? 81. How is journey¬ 

ing most beneficial? 82. What is said of horseback riding? 83. 
What are gymnastic exercises ? How are the muscles affected by this 
kind of exercise ? 84. What is calisthenics ? 85. How should gym¬ 
nastic or calisthenic exercises be practised at first ? What caution is 
to be observed after taking this kind of exercise ? 86. What is said 
of walking?—How should walking be practised? 87. What are the 
advantages of collecting specimens for exercise? 88. When is tho 
best time for taking exercise ? 

USE OF THE EYES. 

89. What is said of the organ oi vision ? 90. For what special 
purpose is the eye formed ? How is it adapted to viewing objects ? 
What objection to long continued application of the eyes to small ob¬ 
jects? 91. Why is artificial light more liable to prove injurious to 
the eyes than daylight ? 

92. In what rays is artificial light deficient ? When are the eyes 


QUESTIONS TO APPENDIX. 


303 


most liable to be injured by artificial light ? 93. What should be the 
position of the light? 94. At what hour are the eyes often injured? 
Why are the eyes more liable to be injured at this hour ? 95. Why 
do the eyes require a short season of rest between daylight and dark ? 
96. What is said of weak eyes ? How are weak eyes to be man¬ 
aged. Repeat rule first—second—third—fourth—fifth. 


BATHING. 

102. What is said of the antiquity of the practice of bathing ? 
What ancient nations practised ablutions ? How were the bathing 
establishments of the Romans constructed ? How do the English and 
Americans of the present day compare with other nations in their 
habits of cleanliness ? 103. What evils arise from habits of uncleanli¬ 
ness ? 104. Is ablution a necessity or a mere luxury that can be dis¬ 
pensed with ? 105. What is said of the pleasure of bathing ? 106. 
How was water regarded by the ancients ? 107. How is water ap¬ 

plied to the skin ? 108. What is the temperature of a cold bath ?—a 
tepid bath ?—a warm bath ? 109. How may a cold bath be applied ? 
110. What is said of the plunge bath?—of swimming? 111. What 
is a douche? 112. How may a shower bath be applied? What ob¬ 
jection to shower baths as they are often constructed ? What are the 
effects of the shower bath when properly managed ? How should the 
shower be regulated ? 113. Describe the effects of the cold bath. 
When there is not a healthy reaction, what are its effects ? What per¬ 
sons are liable to be injured by cold bathing ? 

On what does the ability to practise cold bathing depend ? How 
should the bather commence at first? 114. What are the effects of 
the tepid bath ? 115. When is the best time for a cold bath ? What 
objection to bathing after a full meal? 116. How long should a cold 
bath continue? 117. What are the effects of the warm bath? How 
does the hot bath act? 118. What is a water bath? 119. What is a 
transition bath ? How is it practised in Russia ? 120. When may a 

vapor bath be taken ? 121. How is the frequency of bathing to be 
determined ? How often should children be bathed ?—persons in full 
health ? What are the advantages of daily bathing ? 

CLOTHING. 

122. What relation has the dress to the character of men ? How 
do different persons dress ? On what does our personal appearance 


304 


CLASS-BOOK OF PHYSIOLOGY. 


depend ? Wliat is the effect of indifference to the customs and habits 
of others in respect to dress? How is the fop esteemed ? 123. What 

style of dress is most to be commended? What is more important 
than personal appearance ? 124. What kind of clothing do we require 
during summer ? 125. What is the object to be sought in winter 

clothing ? 126. What is said of woollen ?—of silk ?—of fur ? W'hat 

objections to fur? 

127. On what should the amount of clothing depend ? 128. When 
is the greatest amount of clothing required ? 129. On what other cir¬ 
cumstances should the amount of clothing depend? 130. When is it 
necessary to put on extra clothing ? What is said of the habit of 
“ bundling vp ” ? 131. What are the benefits derived from under¬ 
garments ? 132. Of what importance is the form and size of gar¬ 

ments ? How should the garments be made ? What objections to 
tight garments ? 133. At what period of life is the folly of following 
fashion most apparent? What are the objections to dressing children 
with their arms and necks bare ? 

134. What organs are exposed by wearing low dresses ? 


BLEEDING. 

135. How may bleeding be caused? 136, How may we know 
whether bleeding is from a vein or an artery ? 137. How may arte¬ 
rial bleeding be arrested ? 


RULES FOR THE PRESERVATION OF HEALTH. 


Evert apartment we occupy should be provided with 
some efficient means of ventilation, by which the impure 
gasses may be conducted off, and a constant supply of pure 
air secured. 

The meals should always be taken at uniform intervals, 
and the appetite not indulged at irregular hours. 

The food should be plain and substantial, and not taken 
in haste or in a passion. 

Fruit and vegetables, when fully ripe, are conducive of 
health, if used in moderate quantities with other food. 
Berries should be used within twenty-four hours after 
picking, or they are liable to become highly injurious 
from the commencement of the process of acetous fer¬ 
mentation. 

After dinner there should be at least half an hour’s 
leisure and rest from active labor. Students and men of 
sedentary habits should take not less than an hour for 
recreation or gentle exercise. 

Children under three years of age enjoy better health 
without animal food, and from three to seven it should be 
allowed only in moderate quantities. 

The clothing should always be adapted to the season of 
the year, and as nearly uniform as possible, though the 
habiliments of winter should not be exchanged for those 
of summer till the weather becomes permanently warm 
and mild. By wearing an abundance of warm clothing 
during winter, less food and less artificial heat are 
required, and there is less susceptibility to colds from 
exposure to sudden changes of temperature. 




806 


CLASS-EOOK OF PHYSIOLOGY. 


Sleeping apartments should be cool and well ventilated* 
Hair beds are much better than feathers. 

Children of all ages should spend some portion of every 
day, when not stormy, in the open air. 

Children under seven years should not be confined in 
school more than four hours each day, and that time 
should be broken by frequent recesses. 

Students should train their minds to act with correct¬ 
ness and energy for limited periods of time, and then use 
a spare diet, with three or four hours daily exercise in the 
open air, and occasional vacations of complete exemption 
from study. 

Young persons of both sexes, whatever their occupa¬ 
tion, should spend at least two hours each day in active 
exercise in the open air. 

Every person in full health should wash all over in 
cold water <every morning. 


GLOSSARY AND INDEX 


THE FIGURES REFER TO THE PARAGRAPHS. 


A 

Abdo'men (L. abdo, to hide). So called from its containing the intestines, 
&>c. [89.] 

Abduc'tor (L. abduco, to draw from). Abducent. A muscle, whose office 
is to draw one part of the body away from another. 

Absorp'tion. The act or process of imbibing or swallowing. [31-196.] 

Absorb'ents. Vessels which imbibe, as lymphatics and lacteals. [199.] 

Albi'no. A white descendant of black parents. 

Albu'men (L. albus, white). Albumen is of two kinds, animal and veget¬ 
able: 1 . Animal albumen exists in two forms, the liquid and the solid. In 
the liquid state, it is a thick glairy fluid, constituting the principal part of 
the white of egg. In the solid state, it is contained in several of the tex¬ 
tures of the body, as the cellular membrane, the skin, glands and vessels.— 
2. Vegetable albumen closely resembles animal albumen, and has been 
found in wheat, rye, barley, peas, and beans. [46.] 

Amphib'ia. The second class of the Vertebrata, comprising amphibious ani¬ 
mals, which commence their larva state as fishes, and undergo various 
degrees of metamorphoses in advancing towards the condition of reptiles, 
as the frog, &c. [150.] 

An'imal-heat. [123.] 

Anastomo'sis (Gr. ana, through, and stoma, a mouth). The communication 
of vessels with each other, as of the arteries with the veins, which, by 
touching at numerous points, form a net-work or reticulation. See Inos¬ 
culation. 

Anat'omy (Gr. anatemnd, to cut up). The science of organization; the 
science whose object is the examination of the organs or instruments of 
life. Animal anatomy is divided into human anatomy and comparative 
anatomy, according as it treats of the organization of the human body, or 
of that of other animals. [9.] 

An^tennae. The horns or feelers of insects. 

Aor'ta (Gr. aer, air, tereo, to keep ; as having been formerly supposed to 
contain only air.) The great artery of the heart. It is distinguished into 
the ascending and descending. [65.] 

Aq'ueous. Watery. 

Arach'noid Mem'brane (Gr. arachne, a spider, and eidos t likeness). The 
fine cobweb-like membrane situated between the dura and pia mater. It 
i b the serous membrane of the cerebro-spinal centres. [299.] 



308 


CLASS-BOOK OF PHYSIOLOGY 


Ar'bor Vi't®. Literally, tree of life. A term applied to the arborescent 
appearance presented by the cerebellum, when cut into vertically. [298.] 
Ar'tery (Gr. aer, air, and tereo, to hold). A vessel which carries the blood 
from the heart; formerly supposed, from its being found empty after death, 
to contain only air. 

Aryt'®noid (Gr. aruiaina, a ewer, and eidos, likeness). A term applied to 
two triangular cartilages of the larynx. [478.] 

Au'ditory (L. audio, to hear). Belonging to parts connected with the sense 
of hearing. [359.] 

Auric'ula (L. dim of auris, the ear). An auricle ; the prominent part of the 
ear. Also, the name of two cavities of the heart. [57.] 

Automatic Motions (Gr. automatos, of his own accord). Those muscular 
actions which are not dependent on the mind. 

Autom'aton. A self-moving machine. 

B 

Ball-and-Sock'et. A species of movable articulation, as that of the hip. 
Bicuspida'ti (L. cuspis, a spear). Having two tubercles; as applied to the 
two first pairs of grinders in each jaw. 

Bi'lis. Bile, gall, or choler; the secretion of the liver. [63.] 

Bil'ious. A term employed to characterize a class of diseases caused by a 
too copious secretion of bile. 

Bi'valve. An animal having two valves. 

Brain. [295.]—Of a fish. [282.]—Of a bird. [283.] 

Bronch'us (Gr. brongchos, the windpipe, from brecho, to moisten). The wind¬ 
pipe ; a ramification^of the trachea ; so called from the ancient belief that 
the solids were conveyed into the stomach by the (Esophagus, and the fluids 
by tI-3 bronchia. [100.] 

Bronch'ial-tubes. The minute ramifications of the bronchi, terminating in 
the bronchial cells, or air cells of the lungs. 

Bronchi'tis. Inflammation of the bronchi, or ramifications of the trachea. 
Bur's.® Muco's® (; mucous bags). Small sacs situated about the joints, being 
parts of the sheaths of tendons. ^ 

C®'cum, or Cce'cum (L. coecus, blind). The first part of the colon, or blind 
intestine. 

Cai/lus (Latin, hardness). New bone, or the substance which serves to join 
together the ends of a fracture, and to restore destroyed portions of bone. 
Can'cer. Literally, a crab. The term is applied to the disease from the 
claw-like spreading of the veins. 

Canine'-Teeth (L. canis, a dog). Eye-teeth; the four immediately adjoining 
the incisors. [143.] 

Cap'illary (L. capillus, a hair). Resembling a hair in size; a term applied 
to the vessels which intervene between the minute arteries and veins. 
Capsu'la (L. dim. of capsa, a chest). Literally, a little chest. A capsule or 
bag, which incloses any part. [144.] 



GLOSSARY AND INDEX. 


309 


Car'bon (L. carlo, a coal). A substance well known under the form of coal, 
charcoal, lamp-black, &c. In chemical language, it denotes the pure in¬ 
flammable principle of charcoal; in its state of absolute purity, it constitutes 
the diamond. 

Carbon'ic Acid. Carbon and oxygen combined. [12-114.] 

| Car'dia (Gr. kardia, the heart). The entrance into the stomach, so called 
from being near the heart. [159.] 

[ Car'diac (Gr. kardia, the heart). Relating to the heart. 

I Carniv'orous (L. caro-voro). Eating flesh. 

Carot'id (Gr. karoo, to induce sleep). The name of two large arteries of 
the neck; so called from an idea that tying them would induce stupor. 

I Car'pus (Gr. karpos, fruit). The wrist. The ossa carpi, or carpal bones, 
are eight in number, and form two rows. [444.] 

1 Car'tilage. Gristle. It is attached to bones, and must be distinguished 
from the ligaments of joints and tendons of muscles. [88.] 

Cau'da Equi'na, or horse’s tail; the final division of the spinal cord ;so called 
from the disposition of the nerves which issue from it. 

Cerebel'lum (dim. of cerebrum). The little brain, situated behind t£ e larger, 
or cerebrum. [295.] 

Cer'ebrum (Gr. kart, the head). The brain ; the chief portion of the brain, 
occupying the whole upper cavity of the skull. [281.] 

| Cer'ebro-spinal. System. [285.] 

| Cer'vix. The neck ; the hinder part of the neck: the fore part is called 
collum. 

Chest. Thorax. An old English term, commonly traced to the Latin 
cista. —■“ When it is considered that the same word was anciently used for 
a basket, the appropriation of it to the human thorax will appear quite 
natural to any one who has ever seen a skeleton.”— Forbes. [102.] 

L Chyle (Gr. chulds, juice). The milk-like fluid absorbed by the lacteal 
vessels. [22.] 

|j Chylifica'tion (L. fio, to become). The process by which the chyle is sepa¬ 
rated from the chyme. 

i Chyme (Gr. chumds, juice). The semi-fluid matter which passes from the 
stomach into the duodenum. [22-175.] 

I Chymifica'tion (L. fio, to become). The process by which the aliment is 
converted into chyme. 

I Cil'iary (L. cilia, eyelashes). Belonging to the eyelids. [371.] 

3 Cil'iary Cir'cle or Lig'ament. A kind of grayish ring, situated between 
the choroid membrane, the iris, and the sclerotica. 

! Cil'iary Pro'cesses. Small membranous bodies, surrounding the crystalline 
lens in a radiating form. 

Cineri'tiods (L. cineres, ashesL Ash-colored; a term applied to the exterlai 
or cortical part of the brain, 

[j Clavic'ula (dim. of clavis, a key). The clavicle, or collar-bone; so called 
from its resemblance to an ancient key. [442.] 






310 


CLASS-BOOK OF PHYSIOLOGY. 


Coc'cyx (Gr. kolckux, a cuckoo). The lower end of the spine; so called 
from its resemblance to the cuckoo’s beak. [426.] 

Cocr'lea (Gr. kochlos, a conch). A cavity of the ear, resembling the spiral 
shell of the snail. [358.] 

Co'LOi't (Gr. koldn, quasi koilon K hollow). The first of the large intestines, 
commencing at the coecum, and terminating at the rectum. [185.] 

Co'ma (Gr. koma, drowsiness, from ked, to lie). Drowsiness; lethargic sleep; 
dead sleep; torpor. 

Com'missure (L. commissura ). To joint or sever the place where two bodies 
or parts of a body meet and unite. 

Con'dyle (Gr. kondulos, a knuckle). A rounded eminence in the joints of 
several bones, as of the humerus and the femur. [447.] 

Congestion (L. congero. to amass). Undue fullness of the blood-vessels. 

Conjunc'tiva (L. conjungo, to unite). The mucous membrane which lines 
the posterior surface of the eyelids, and is cc» tinued over the fore-part of 
the globe of the eye. [374.] 

Cor'acoId Pro'cess (Gr. korax, a crow, and eidos, likeness). The upper 
and anterior point of the scapula; so called from its resemblance to a 
crow’s beak. 

Co'rium. Leather. The deep layer of cutis, or true skin, forming the basis 
of the support to the skin. 

Corn'ea (L. cornu, a horn). The anterior transparent portion of the globe 
of the eye. [376.] 

Corpus'culum (L. dim. of corpus, a body). A corpuscle, or little body. 

Cra'kium (Gr. kdra, the head). The skull, or cavity which contains the 
brain, its membranes, and vessels. [295.] 

Crib'riform (L. cribrum, a sieve, and forma, likeness). The name of the 
plate of the ethmoid-bone, from its being perforated like a sieve. 

Cri'cos (Gr. krikos, a ring). Whence Cricoid, the name of the ring-like 
cartilage of the larynx. [477.] 

Crys'talline (Gr. krustallos, ice). A. term applied to the lens of the eye 
[376.] 

Cuboi'des (Gr. kubos, a cube, and eidos, likeness). The name of a bone of 
the foot, somewhat resembling a cube, situated at the fore and outer part 
of the tarsus. 

Cuneiform (L. cuneus, a wedge, and forma, likeness). Wedgelike; the 
name of three bones of the foot. 

Cu'ticle (L. dim. of cutis). The epidermis, or scarf-skin. [247.] 

Cu'tis (Gr. kutos, the skin). The true skin, as distinguished from the cuticle, 
epidermis, or scarf-skin. 

D 

Degltjti'tion (L. deglutio, to swallow). The act of swallowing. [156.] 

Di'aphragm (Gr. didphragma, a partition). The midriff: the transverse 
muscular partition which separates the thorax from the abdomen. [103,] 


GLOSSARY AND INDEX. 


311 


Diges'tion (L. digero, from diversim gero, to carry into different parts). In 
Physiology , the change of the food into chyme by the mouth, stomach, and 
small intestines; and the absorption and distribution of the more nutritious 
parts, or the chyle , through the system. [133.] 

Dor'sum (Latin). The back; the round part of the back of a man or beast. 
Whence Dor 1 sal, appertaining to the back, as applied to a region, 
ligaments, &c. [426.] 

Drop'sy (L. hydrops, from the Gr. iidrops, water). An effusion of serous 
fluid into any of the natural cavities of the body. 

Duode'num (L. duodeni, twelve). The twelve-inch intestine; so called from 
its being equal in length to the breadth of twelve fingers; the first portion 
of the small intestines, beginning from the pylorus. [181.] 

Du'ra Ma'ter (hard-mother). The outermost membrane of the brain. [299.] 

Dys'entery (Gr. dus, badly, and entera, the bowels). Inflammation of the 
mucous lining of the large intestines. 

Dyspepsia (Gr. dus, and pepto, to digest). Indigestion; difficulty of diges¬ 
tion. [171.] 

E 

Efflu'via (L. effluo, to flow out). Exhalations, vapors, &c. 

Elasti'city. The properly or power by which a body compressed or 
extended returns to its former state. 

Eleva'tor (L. elevo, to raise). A name applied to certain muscles, whose 
office it is to elevate any part. 

Enam'el. The hard exterior surface of the teeth. [146.] 

Enceph'alon (Gr. en, in, kephale, the head). The brain; the contents of 
the skull, consisting of the cerebrum, cerebellum, medulla oblongata, and 
membranes. 

Epider'mis (Gr. epi, upon, and derma, the skin). The cuticle, or scarf-skin; 
the thin horny layer which protects the surfade of the integument. [244.] 

Epiglot'tis. A cartilage of the larynx, situated above the glottis. 

Epip'loon (Gr .pleo, to sail). The omentum; a membranous expansion which 
floats upon the intestines. 

Epithe'lium (Gr. tithemi, to place). The cuticle on the red part of the lips, 
and on the mucous membranes in general. 

Eth'moid (Gr. ethvids, a sieve, eidos, likeness). Cribriform, or sieve-like; a 
bone of the nose, perforated for the transmission ol the olfactory nerves. 

Eustach'ian-tube. The canal which extends from the tympanum to the 
pharynx, called after Eustaehius, its discoverer. [353.] 

Excre'tion (L. excerno, to separate from). A general term for the perspira¬ 
tion, faeces, &c., which are separated and voided from the blood, or the 
food. [230.] 

Expira'tion (L. expiro, to breathe). That part of the respiration in which 
the air is expelled. Compare Inspiration. 

Exuda'tion. Transpiration. The flow of liquid from the surface of the 
skin or membrane, an ulcer, &c. 






312 


CLASS-BOOK OF PHYSIOLOGY. 


F 

Fa'cet. A little face, a small surface. 

Fa'cial (L, facies, the face). Belonging to the face; as facial nerve, facial 
vein, &c. 

Falx. A scythe or sickle. The sic&Ze-like processes of the dura mater, 
situated between the lobes of the cerebrum and cerebellum. [300.] 

Fas'cia (L. fascis, a bundle). Literally, a scarf or large band. Hence it is 
applied to the aponeurotic expansion of a muscle. 

Fascic'ulus (L. dim. of fascis, a bundle). A little ^bundle ; a handful. 
Thus, a muscle consists of fasciculi of fibres. [33.] 

Fau'ces. The gullet or upper part of the throat; the space surrounded by 
the velum palati, the uvula, the tonsils, and the posterior part of the tongue. 

Fe'mur, Fem'oris. Os femoris. The thigh-bone, the longest, largest, and 
heaviest of all the bones of the body. [447.] 

Fenes'tra (Gr. phaind, to shine). Literally, a window; an entrance into 
any place. Hence the terms fenestra ovalis and rotunda, or the oval and 
round apertures of the internal ear. 

Fi'bre (L .fibra, a filament). A filament or thread, of animal, vegetable, or 
mineral composition. [28.] 

Fi'bril. A small filament, or fibre, as the ultimate division of a nerve. The 
~m is derived from fibrilla, L. dim. of fibra, a filament. 

Fi'brin. A tough fibrous mass, which, together with albumen, forms the 
basis of muscle. [49.] 

Fi'bro-car'tilage. Membraniform cartilage: a substance intermediate be¬ 
tween proper cartilage and ligament. [349.] 

Fib'ula. Literally, a clasp, or buckle. It denotes the lesser bone of the 
leg. [448.] 

Fil'ament (L. filum, a thread, forma, likeness). Thread-like; applied to 
the papillae at the edges of the tongue. 

Fis'sure. A cleft, a longitudinal opening. 

Flex'or (L. flecto, to bend). A muscle which bends the part into which it 
is inserted. Its antagonist is termed extensor. 

Fll'ids. Substances which have the quality of fluidity, and are, in conse¬ 
quence, of no fixed shape. 

Fol'licle (L. dim. of follis, a pair of bellows). Literally, a little bag, or scrip 
of leather; in anatomy, a very minute secreting cavity. [168.] 

Fora'men (L. foro , to pierce). An opening. [356.] 

Fos'sa (L. fodio, to dig). A ditch or trench; a little depression, or sinus. 

Func'tion (L. fungor, to discharge an office). The office of an organ in the 
animal or vegetable economy, as of the heart in circulation, of the leaf in 
respiration, &c. [18.] 

Fu'siform (L. fusus, a spindle, forma, likeness). Spindle-shaped; a term 
applied to certain muscles. 


GLOSSARY AND INDEX. 


313 


G 

Gall'-blabder. a membranous reservoir, lodged in a fissure on the under 
surface of the right lobe of the liver, and containing the bile. [191.] 

Gall'ducts. These are the cystic, proceeding from the gall-bladder; the 
hepatic, proceeding from the liver; and the ductus communis choledochus, 
resulting from the union of the two preceding. 

«?an glion (Gr. gangglion, a nerve-knot). A small nervous centre, or an 
enlargement in the course of a nerve, sometimes termed a diminutive 
brain. [262.1 

Gas'tep,, The Greek term for the stomach. 

Gas'tric (Gr. gaster, the stomach). Pertaining to the stomach; ao the 
gastric juice, &c. 

Gas'tric Juice. The peculiar digestive fluid secreted by he stomach. [167.] 

Gei/atine (L. gelu, frost). The principle of jelly. It is found in the skin, 
cartilages, tendons, membranes, and bones. The purest variety of gelatine 
is isinglass. 

Gin'glymus (Gr. gigglumos, a hinge). The hinge-like joint; a species of 
articulation admitting of flexion and extension. 

Giz'zard. Of bird. [160.] Insect. [161.] 

Gland (L. glans, glandis, an acorn). A soft body, composed of various tis¬ 
sues, vessels, nerves, &e., usually destined to separate some fluids front 'ie 
blood. [150.] 

Gle'noid (Gr. glene, a cavity, eidos, likeness). The name of a part having 
a shallow cavity, as the socket of the shoulder-joint. 

Glob'ules Red (L. dim. of globus, a ball). The red coloring matter of the 
blood; a peculiar animal principle. 

Glos'sa, or Glot'ta (Gr. glotta). The tongue; the organ of speech.— 
Glosso-. Terms compounded of this word belong to nerves or muscles 
attached to the tongue. 

Glot'tis. The aperture of the larynx between the arytaenoxd cartilages. It 
is covered by a cartilage called the epi-glottis. 

Gran'ule. A small particle. 

Great Sympathetic. A nerve formed by a collection of filaments from 
every nerve, which join each other at the adjacent ganglia. 

H 

Hjem'atosin (Gr. haima, blood). A characteristic constituent of the blood, 
derived from the globules. 

Hjem'orrhage. A rupture of a blood-vessel; a bursting forth of blood; 
loss of blood. 

Herbiv'orous (L. herba, and vora). Eating herbs. 

Hepat'ic. A term applied to any part belonging to the liver. [236.] 

Hexag'onal. Having six sides and six angles. 

Hu'merus. The bone of the upper-arm. [443.] 

Hu'mor (L. humeo, to be moist). An aqueous substance; as the humors cf 
the eye. 


23 



314 


CLASS-BOOK OF PHYSIOLOGY. 


Hy'dra (Gr. udor, water). A polype indigenous in our brooks, destitute ol 
a stomach, brain, viscera, or lungs. [84.] 

Hy'giene (Gr. to be well). Health; the preservation of health; that part 
of medicine which regards the preservation of health. 

Hyoi'des (the Greek letter upsilori). A bone situated between the root of 
the tongue and the larynx. 

HYro-GAs'TRiUM. The lower anterior region of the abdomen. 

Hypo-glos'sal. The name of the lingualis, or ninth pair of nerves, situated 
beneath the tongue. [303.] 

h J 

Ich'or. A thin acrid discharge, issuing from wounds, ulcers, &c. 

Jeju'num (L. jejunus, hungry). The npper two-fi ths of the small intestines, 
so named from this portion being generally found empty. 

Il'eum (to turn about). The lower three-fifths of the small intestines , so 
called from their convolutions, or peristaltic motions. 

Ii/iac-Bone. Another name for the os innominatum, derived from the cir¬ 
cumstance that this compound bone supports the parts which the ancients 
called ilia, or the flanks. 

Il'iac Region. The region situated on each side of the hypogastrium. 

In'cus (an anvil). A small bone of the internal ear, with which the malleus 
is articulated; so named from its fancied resemblance to an anvil. 

In'dex (L. indico, to point out). The fore-finger ; the finger usually employed 
in pointing at any object. 

Infra-sfina'tus. A muscle arising from the scapula below the spine, and 
inserted into the humerus. 

Innomina'tus (L. in, priv., nomen, name). Hence Innominatum os, a bone 
composed of three portions, viz: 1, The ilium, or haunch-bone. 2, The 
ischium, or hip-bone. 3, The os pubis, or share-bone. 

Insaliva'tion. [153.] 

In'stinct. This convenient term admits of the following significations: 1. 
The Instinctive Faculty; or that faculty which leads the duckling, un¬ 
taught, into the water; the beaver to build its hut; the bee its comb; the 
hen to incubate her eggs, &c.; and, 2. The Instinctive Motions; or those 
involuntary actions which are excited mediately through the nerves—a part 
of the reflex function. 

Integ'ument (L. in, and tego, to cover) The covering of any part of the 
body, as the cuticle, cutis, &c. 

Inter-cos'tal. The name of two sets o muscles between the ribs—the 
external and the internal. [104.] 

Intes'tines (L. intus, within). That part' of the alimentary canal which 
extends from the stomach to the anus. [183.] 

Pris. Literally a rainbow; and hence applied to the rainbow-like membrane 
which separates the ulterior from the posterior chamber of the eye. [377.] 

Ju'gular. Belonging to the neck; applied chiefly to the principal veins of 
the neck. 


GLOSSARY AND INDEX. 


315 


K 

Kingdom. A term denoting any of the principal divisions of nature; thus 
we have the organic kingdom, comprehending substances which organize} 
and the inorganic kingdom, comprehending substances which crystallize. 

Knee'pan. Patella; the small round bone at the front of the knee-joint. 

Kid'neys. Two oblong glands, which secrete the urine. [235.] 

L 

La'bia. The lips. They are laterally united by means of two acute angles, 
which are called their commissures. 

Lab'yrinth. The name of a series of cavities of .he inner ear; viz: the 
vestibule, the cochlea, and the semi-circular canate. 

Lach'ryma. A tear; the fluid secreted by the lachrymal gland, and flowing 
on the surface of the eye. 

Lac'teals (L. lac, milk). Numerous minute tubes which absorb or take up 
the chyle, or milk-like fluid, from the alimentaiy canal. [188.] 

Lac'tic Acid ( L. lac, lactis, milk). An acid produced whenever milk, and 
perhaps most animal fluids, become spontaneously sour. 

Lam'ina. Literally, a small plate of any metal. A term applied to the 
foliated structure of bones or other organs. 

La'rynx (Gr. larungx, the larynx). The superior part of the trachea, 
situated immediately under the os hyoldes. [97.] 

Lens (L. lens, lentis, a bean). Properly, a small roundish glass, shaped like 
a lentil, or bean. [391.] 

Lig'ament (L. ligo, to bind). A membrane of a flexible but compact texture, 
which connects the articular surfaces of bones and cartilages; and some¬ 
times protects the joints by a capsular envelope. 

Lin'gua (L. lingo, to lick). The tongue; the organ of taste and speech. 

Liv'er. The largest glandular apparatus in the body, the office of which is 
to secrete the bile. [191.] 

Lob'ulus (L. dim. of lobus, a lobe). A lobule, or small lobe. [236.] 

Lu.m'bi. The loins; the inferior part of the back; whence Lumbar, the 
designation of nerves, arteries, veins, &c., belonging to the region of the 
loins. 

Lungs. The organs of respiration. [95.] 

Luxa'tion (L. luxo, to put out of joint). Dislocation ; or the removal of the 
articular surface of bones out of their proper situation. 

Lymph (L. lympha, water). A colourless liquid which circulates in the 
lymphatics. [22.] 

Lymphat'ics (L. lympha, water). Minute tubes which pervade every par* 
of the body, which they absorb, or take up, in the form of lymph. [99.] 

M 

Magne'sium. A metal having the color and lustre of silver. 

Malleo'lus (L. dim. of malleus, a mallet). The ankle, so called from it* 
resemblance to a mallet. 


316 


CLASS-BOOK OF PHYSIOLOGY. 


Mamma (L. mamma, a teat). The fifth class of the Vertebrata, consisting 
of animals provided with mammary glands for the suckling of their young 
after birth. 

Man'dibles. The jaws of a bird. 

Mas'seter (Gr. to chew). A muscle which assists in chewing. 

Mas'toid (Gr. a breast). Shaped like the breast or nipple; as applied Id a 
process, and a foramen of the temporal-bone. 

Mea'tus (L. meo, to pass, to flow). Literally, a passage. 

Met>tjl'la. Marrow ; a kind of fixed oil, occupying the cavities of bones. [2.J 

Medul'la Oblongata. The upper enlarged portion of the spinal cord. [291.] 

Melui/la Spinalts. The spinal marrow or cord. 

Medul'lary. The designation of the white substance of the brain. [339.] 

Mr/entery (Gr. between the bowels). The membrane which connects the 
small intestines and the posterior wall of the abdomen. 

Meta-car'pus (Gr. after, the wrist). That part of the hand which is situated 
between the carpus and the fingers. 

Me:a-tar'sus. That part of the foot which is situated between the tarsus 
and the toes. [250.] 

Mil'riff. Diaphragm. The muscle which divides the body into the thorax 
and the abdomen. 

Mi'tral Valves (L. mitra, a mitre). The name of two valves which guaru 
the left ventricle of the heart. 

Mg'la.r (L. mola, a mill-stone). The double or grinding teeth. Those with 
two fangs are called bicuspid, or false molars. 

Mot/luscs. Animals without an internal skeleton or articulated covering. 

Mo'tor (L. moveo, to move). A mover; a part whose function is motion. 

Mu'cus. The liquid secreted by the mucous surfaces, as of the nostrils, 
intended as a protection to the parts exposed to external influences. 

N 

Narcot'ics (Gr. stupor). Medicines which indue*, s.eep or stupor, as opiates 

Na'sus. The nose, or organ of smell; whence nasal, belonging to the nose. 
[333.] 

Nerves (L. nervus, a string). White cords arising from the brain or the 
spinal marrow, and distributed to every part of f b*» system. [250.] 

Neurai/gia. Nerve-ache, or pain in the nerve. 

Neu'ron (Gr.). A nerve; a cord arising from ♦he brain or spinal marrow, 
whence Neurilemma, the sheath of a nerve ami Neurology, the doctrine 
of the nerves. 

Nig-'tating. Winking. 

Ni'trogen. Azote. An elementary principle, constituting four-fifths o*. the 
volume of atmospheric air. 

Nu'cleus. The kernel of a nut. The centre around which partic es are 
aggregated. 

Nutri'tion (L. nutrio, to nourish). The process of nourishing the frame. 
[16-218.] 


GLOSSARY AND INDEX. 


317 


O 

Obu'qtjtjs. Oblique or slanting; not direct,perpendicular or parallel,applied 
to several muscles. 

Obtgra'tor (L. obturo, to stop up). The name of two muscles of the thigh, 
and of a nerve. 

Oc'cjput (L. ob caput). The back part of the head; the part opposite to the 
front or sinciput. 

(Esoph'agus (Gr. to carry, to eat). A cana. eading from the mouth to the 
stomach. [153.] 

Oleag'inous (L. oleum, oil). That which contains, or resembles, oil. 

Olec'ranon. The large apophysis, constituting the elbow, or head of the ulna. 

Olfac'torv (L. olfacio, to smell). Belonging to the smell; the name of the 
first pair of cerebral nerves, &c. [282.] 

Omen'tum. The caul; a fold or reflexion of the peritoneum. 

Omo (Gr. the shoulder). Words compounded with this term belong to mus¬ 
cles attached to the scapula. 

Op'tic. Belonging to the sight. [281.] 

Orbicula'ris. The name of two muscles of the face. 

Or'bit (L. orbita, an orbit, a track). The cavity under the forehead, in which 
the eye is fixed. [370.] 

Or'gan. A part which has a determinate office in the animal economy. [36.] 

Organization. A term applied to a system, composed of several individual 
parts, each of which has its proper function, but all conduce to the exist¬ 
ence of the entire system. 

Ok'igin (L. origo). The commencement of a muscle from any part. Its 
attachment to the part it moves is called its insertion. 

Os, Ossis. A bone; a portion of the skeleton, constituting a passive organ 
of locomotion, as distinguished from a muscle, or active organ of this faculty. 

Ossifica'tion. The formation of bone; the deposition of calcarious phos¬ 
phate, or carbonate, on the soft solids of animal bodies. 

Ot'olites (Gr. the ear, a stone). Calcarious concretions found in the 
labyrinth of fishes and fish-like amphibia, which, by being in contact with 
the membranous parts of the labyrinth, increase by their resonance the 
sonorous vibrations. 

Ox'ides. Substances combined with oxygen, without being in the state of 
an acid. 

Ox'ygen. A gas which forms about a fifth of atmospheric air, is capable of 
supporting flame, and is essential to the respiration of animais. 

P 

Pan'creas. A gland, situated transversely across the posterior wall of the 
abdomen. In cattle it is called the sweet-bread. [189.] 

Pancreat'ic Juice. The peculiar fluid secreted by the pancreas.* [163.] 

Papil'la. The term papilla denotes the small eminences which constitute 
the roughness of the upper surface of the tongue. [27.] 


318 


CLASS-BOOK OF PHYSIOLOGY. 


F'aral'ysis. Palsy; the total loss, or diminution, of sensation or of motion 
or of both. 

Parot'jd. The name of the large salivary gland situated near the ear. [153.] 

Par'ies Pari'etis. The wall of a house, or any other building; whence 
Parietal, belonging to the walls of an organ. 

Patel'la (L. dim. of patina , a pan). Literally, a small pan. The knee-pan. 

Pathet'ic (Gr. passion ). A name given by Wiilis to the fourth pair of nerves, 
because the eyes, by means of these, express certain passions. [303.] 

Pec'toral (L. pectus, the breast). Pertaining to the breast. 

Pectoral 'is. The name of two muscles of the trunk. 

Pe'dal (L. pedules). Pertaining to a foot. 

Pel' vis (Gr. a basin). The basin, or large bony cavity which terminates the 
trunk inferiorly. [HO.] 

Pericar'dium (Gr. around the heart). A fibro-serous membrane which 
surrounds the heart. [61.] 

Pericra'nium. The periosteum or membrane which covers the bones of the 
cranium. 

Perios'teum. The membrane which surrounds the bones. 

Peristal'tic. A term applied to the vermicular contractions of the intes¬ 
tines upon themselves. 

Peritoneum. The serous membrane which lines the interior of the abdomen, 
and invests all the viscera contained therein. 

Permeabil'ity (L. per, through, mco, to pass). That property of certain 
bodies by which they admit the passage of other bodies through their 
substance. 

Perspira'tion (L. perspiro, to breathe through). The watery vapor which 
is constantly passing off through the skin. [254.] 

Pija'lanx. A battalion in the Macedonian armies, composed of 16,000 men. 
Hence the term phalanges is applied to the bones of the fingers and toes, 
from their regularity. 

Pha'rynx (Gr. the throat). A musculo-membranous bag, situated at the 
back part of the mouth, leading to the stomach. 

Phre'nes (Gr. the mind). The diaphragm; so called because the ancients 
supposed it to be the seat of the mind. Hence the term Phrenic, a desig¬ 
nation of the internal respiratory nerve, which goes to ttie diaphragm. 

Phrenol'ogy (Gr. an account). A description of the mind; a science, 
introduced by Gall and Spurzheim, by which particular characters and pro¬ 
pensities are indicated by the conformation, and protuberances, of the skull. 

Physiol'ogy (Gr. phusis, nature, logos, an account). The science which 
treats of the properties of organic bodies, animal and vegetable, of the 
phenomena which they present, and of the laws which govern their 
actions. [8.] 

Pi'a Ma'ter. A vascular membrane, investing the whole surface of the 
brain. [299.] 

Pigmen'tum Ni'grum (L. pingo, to paint). A dark brown substance, which 
'.overs the outer and inner surface of the choroid membrane. 


GLOSSARY AND INDEX. 


319 


Pin'na. The fin of a fish. A portion of the external ear, termed pinna 
auricula, or the auricle, representing a kind of funnel, which collects the 
vibrations of the atmosphere. The other portion is termed meatus, and 
represents a tube, which conveys the vibration to the tympanum. 

Pitu'itary Membrane. A designation of the Schneiderian membrane, 
which lines the cavities of the nose. 

Pleu'ra. [106.] 

Plex'us (L. plecto, to weave). A kind of net-work of blood-vessels, or 
nerves. 

Plana'ria. [157.] 

Pneu'mo-Gas'tric Nerves (Gr. pneumon, the lung, gaster, the stomach). 
The par vagnum, nervi vagi, or eighth pair of nerves, distributed to the 
stomach. 

Pol'yfe. A species of fresh-water insect. [136.] 

Por'tal Circula'tion. A subordinate part of the venous circulation, in 
which the blood makes an additional circuit before it joins the. rest of the 
venous blood. 

Por'tal Vein (L. vena porta). A vein originating from the organs within 
the abdomen. [46.] 

Por'tio Du'ra. The hard portion of the seventh pair of nerves, or facial. 
[303.] 

Por'tio Mol'lis. The soft portion of the seventh pair of nerves, or audi• 
tory. [303.] 

Potas'sium. The metallic base of the well-known alkaline substance potassa. 

Prehen'sion. A taking hold, a seizing. 

Prism (Gr. prisma, hamprio, to saw). A solid glass in the form of a tri¬ 
angle, so termed from its separating a ray of light into its constituent parts. 

Pro'cess. Apophysis. A process, or eminence of a bone. Also, a lobe, or 
portion of the brain. 

Prona'tion (L. pronus, bending downward). The act of turning the palm 
of the hand downwards, by rotating the radius upon the ulna by means of 
the pronator muscles. 

Prona'tor (L. pronus, bending downward). The name of two muscles 
which turn the radius and the hand inwards and downwards. 

Prox'imate Prin'ciple. A term applied, in analyzing any body, to the prin¬ 
ciple which is nearest to the natural constitution of the body, and more 
immediately the object of sense, as distinguished from intermediate or ulti¬ 
mate principles. Ultimate principles are the elements of which proximate 
principles are composed. 

Pso'as (Gr. psoai, the loins). The name of two muscles of the loins. 

Pul'monary, pulmonic, (L. pulmo, the lungs). Relating or belonging to the 
lungs. 

Pulse (L. pulsus, a stroke). A beating or striking; and, hence, the stroke 
or beat of an artery. [69.] 

Punc'tum (L. pungo, to prick). A point; that which is without extent. 

Punc'ta Lachryma'lia. The external commencements of the lacrymal ducts. 


320 


CLASS-BOOK OF PHYSIOLOGY. 


Po'pila (L. dim. of pupa, a puppet). The pupil, or the round aperture in tha 
centre of the iris of the eye. [384.] 

Pylo'rus (Gr. pule, a gjite; ora, care). Literally, a gate-keeper. The 
lower and contracted orifice of the stomach, guarding the entrance into 
the bowels. 

Q 

Quartz. A species of silicious minerals. 

It 

Ramification (L. ramus, a branch, fio, to become). The issuing of a small 
branch from a large one, as of the minute branches from the larger arteries. 

Ra'mus. A branch of a tree; the designation of portions of several bones. 

Rec'tum (L. rectus, straight). The last portion of the intestines. 

Rec'tus (L. straight). The name of several muscles. 

R.efrac'tion (L. rcfractus, broken back). That property of light, by which 
a ray becomes bent, or refracted, when passing from a rarer into a densei 
medium, and vice versa. [389.] 

Respira'tion. The function of breathing. 

Ret'ina (L. rete, a net). The neZ-like expansion of the optic nerve on the 
inner surface of the eye. [271.] 

Ri'ma. A fissure, a crack, or cleft; a narrow longitudinal opening. 

‘ Roden'tia (L. rodo, to gnaw). Glires, or gnawing animals, as the beaver, 
the hamster, the rat, &c. 

Ru'ga. A wrinkle. Hence the terms rugose, wrinkled, and rugosity, ap¬ 
plied to a wrinkled surface, as the mucous membrane of the stomach. 

Ruminax'tia (L. rumino, to chew the cud). Animals which chew the cud, 
as the deer. 

Rumina'tion. A voluntary regurgitation of food for further mastication; 
peculiar to the ox, sheep, and other animals having numerous stomachs ; it 
is commonly called chewing the cud. [159.] 

S 

Sac (L. saccus, a bag). A term applied to a small cavity, as the lacrymal 
sac. [90.] 

Sa'crum (L. Sacred). The bone which forms the basis of the vertebral col¬ 
umn, so called from its having been offered in sacrifice, and hence con¬ 
sidered sacred. [426.] 

Sacro-. A term applied to parts connected with the sacrum; hence we 
have sacro-iliac symphysis, sacro-spinal ligament, sacro-vertebral angle. See. 

Sali'va. The insipid, transparent, viscous liquid, secreted by the salivary 
glands, principally the parotid. [153.] 

San'guis. Blood; the fluid which circulates in the heart, arteries, and veins. 

Sartu'rius (L. sartor , a tailor). The muscle by means of which the tailor 
crosses his legs. 

Scap'ula. The shoulder-blade. 

Schneide'rtan Membrane. The pituitary membrane, which eecretes the 
mucous of the nose; so named from Schneider, who first described it. [337.] 


GLOSSARY AND INDEX. 


321 


Sciat'ic Nerve. The termination of the sacral or sciatic plexus; it is the 
largest of all the nerves. 

Sclerot'ica (Gr. sklerds, hard). The dense fibnaus membrane which, with 
the cornea , forms the external tunic of the eye-ball. 

Seba'ceous (L. sebum, suet). Suety; a term applied to follicles which 
secrete a peculiar oily matter, and are abundant in some parts of the skin, 
as in the nose, &c. [257.] 

Secre'tion (L. secerno, to separate). A substance secreted or separated 
from the blood, by the action of a secreting organ. [31.] 

Seg'ment. A part cut off or divided. 

Sep'tum (L. sepes , a hedge). A partition which separates two cavities. 

Serra'tus (L. scrra, a saw). The name of three muscles of the side and back 

Se'rum. The thin yellowish fluid constituent of the blood. [45.] 

Sin'ciput. The fore part of the head. The back part is called occiput. 

Sin'ew. The ligament which joins two bones. 

Si'nds. A gulf. Hence it denotes a cavity or cell within the substance of a 
bone, as of the forehead; also a large venous canal, as those of the dura 
mater. 

Skel'eton (Gr. skello, to dry up). The dry bony frame-work of an animal 
which sustains the other organs. 

Sphinc'ter (L. sphinggo, to contract). A muscle, whose office it is to close 
the aperture around which it is placed. [181.] 

Spi'nal Cord. Medulla spinalis. The medullary matter contained within 
the spine, or vertebral column. [263 ] 

Spleen A spongy organ, situated at the left and behind the stomach. 

Splint'bone. The fibula, or small bone of the leg; so named from its 
resembling a surgical splint. 

Sta'pes. Literally, a stirrup. A stirrup-like bone of the internal ear. [356.] 

Ster'num. The breast-bone. [438.] 

Stigma 'ta. The apertures in the bodies of insects communicating with the 
tracheae or air-vessels. 

Stom'ach of the Hydra. [157.] 

« Planaria. [157.] 

« Sheep. [159.] 

« Bird. [160.] 

« Man. [163.] 

Stu'por (L. stupeo, to be senseless). A state of insensibility. 

Sty (L. stihan, Saxon, a springing up). Stian. A little inflammatory 
tumor on the eye-lid. 

Sub-. A Latin preposition, denoting a position beneath any body. 

Sub-cla'vian. Situated under the clavicle. 

Sub-cla'vius. A muscle arising from the cartilage of the first i:b, and 
inserted into the lower surface of the clavicle. 

Sub-cut a n^eous. Beneath the skin. 

Sub-lin'gual. Beneath the tongue. 



322 


CLASS BOOK OF PHYSIOLOGY. 


Sub-max'illary. Beneath the jaw. 

Su'dor (L. sudo, to sweat). Sweat; the vapor which passes through the 
skin, and condenses on jjie surface of the body. 

Sudorif'erous Canals. Minute spiral follicles, distributed over the whole 
surface of the skin, for the secretion of the sweat. 

Su'ture (L. suo, to sew). A seam; the junction of the bones of the cra¬ 
nium by a serrated line, resembling the stitches of a seam. 

Sympathetic Nerve. A nerve consisting of a chain of ganglia, extending 
along the side of the vertebral column from the head to the coccyx, com¬ 
municating with all the other nerves of the body, and supposed to produce 
a sympathy between the affections of different parts. 

Syno'via (Gr. odn, an egg). A peculiar liquid, found within the capsular 
ligaments of the joints, which it lubricates. 

T 

Tar'sus. The instep; the space between the bones of the leg and the meta¬ 
tarsus. [450.] 

Tears. The peculiar fluid which lubricates the eye. 

Teeth. [143.] 

Tem'fora (L. pi. of tempus, time). The temples, or that part of the head 
on which the hair generally begins to turn gray, thus indicating the age ; 
whence temporal, pertaining to the temples, as temporal bones. 

Tena'city (L. teneo, to hold). The degree of force with which the particles 
of bodies cohere, or are held together. 

Ten'don (L. leind, to stretch). A fibrous cord at the extremity of a muscle, 
by which the muscle is attached to a bone. 

Ten'sor (L. tendo, to stretch). A muscle which stretches any part. 

Tentac'ula. A filliform process or organ on the bodies of various animals. 

Texto'rium(L. tendo, to stretch). A tent, or pavilion, as Tentorium cere - 
belli, a roof of dura mater thrown across the cerebellum. In leaping ani¬ 
mals, it is a bony substance. 

JTho'rax (Gr. thorax). The chest; or that cavity of the body which con¬ 
tains the heart and lungs. [fiO.] 

Thora'cic Duct. The great trunk formed by the junction of the absorbent 
vessels. [209.] 

Thy'roid (Gr. thureds, a shield). The name given to a shield-shaped car¬ 
tilage of the larynx, and of a gland situated on the trachea. 

Tib'ia. Literally, a flute or pipe. The shin-bone; or the great bone of the leg. 

Tjb'ial, tibialis, pertaining to the tibia. 

Tis'sue. A web, or web-like structure, constituting the elementary struc¬ 
tures of animals and plants. [17.] 

Ton'sils (L. tondeo, to clip, or shear). The round glands situated in the 
throat, between the pillars of the velum palati. 

Trach'ea (Gr. trachus, rough). The wind-pipe. The term is derived from 
the inequality of its cartilages. [99.] 

Tract (L. traho, to draw). A drawing in length ; a region; a space. 


GLOSSARY AND INDEX. 


323 


Tri'ceps. Having three heads. Applied to several muscles. 

Tricus'pjd. Having three points; a term applied to three triangular fold® 
or valves situated between the right auricle and the right ventricle of the 
heart. [63.] 

Trifa'cial. Triple-facial; a term applied to the fifth pair of nerves, the 
grand sensitive nerve of the head and face. 

Trochan'ter (Gr. trochao, to run or roll). The name of two processes of 
the thigh-bone—the major and the minor. 

Troch'lea (Gr. trochos, a wheel). A kind of cartilaginous pulley. Hence 

yTrochlearis, a name of the obliquus superior, or that muscle of the eye 
which passes through the trochlea or pulley. '387.] 

Tu'nic. The upper garment of the Romans. Hence it is applied to several 
membranes of the body. 

Tur'binatrd Bones (L. turbo, a top). Two bones of the nostrils, so called 
from the>r being formed in the shape of a top, or inverted cone. They 
are also called the inferior spongy bones, to distinguish them from the 
upper spongy bones. 

Tym'panum (Gr. tumpanon, a drum). The drum of the ear. [351.] 

U 

Ul'na (Gr. blent, the cubit). The large bone of the fore-arm, so named 
from its being often used as a measure, under the term ell. [143.] 

Uve'a (L. uva, grape). The posterior surface of the iris, so called from its 
resemblance in colour to a ripe grape. 

U'vula (L. dim. of uva, a grape). The pendulous body which hangs down 
from the middle of the soft palate. 

V 

Vaucina'tion (L. vacca, a cow). The act of inserting vaccine matter; 
inoculation for the cow-pox. 

Vac'cuum (L. vaccus, empty). Literally, an empty place. This term gen¬ 
erally denotes the interior of a close vessel, from which the atmospheric 
air and every other gas has been - extracted. 

Valve (L. valves, folding-doors). A close fid affixed to a tube or opening in 
some vessel, by means of a hinge, or other movable joint, and which can 
be opened only in one direction. Hence it signifies a little membrane 
which prevents the return of fluid in the blood-vessels and absorbents. 

Val'vt^la (L. dim. of valve). A little valve. 

Vas, Vasts. Plural Vasa. A vessel, or any utensil to hold liquor. 

Vas'cular System. That part of the animal economy which relates to the 
vessels. 

Ve'nous. Belonging to a vein. [75.] 

Ventrio'ulus (L. dim. of venter, the belly). The term ventricle is also 
applied to two cavities of the heart, and to several cavities in other parts 
of the body. 

Vsr'miform (L. vermis, a worm, forma, likeness). Worm-like. 


324 


CLASS-BOOK OF PHYSIOLOGY. 


Vermic'ula. Having a worm-like motion. 

Ver'tebra (L. verto, to turn). A bone of the spine, so named from its turn 
ing upon the adjoining one. [286 ] 

Ver'tebral. Connected with the vertebra. 

Vertebra'ta. Animals which have an internal skeleton, supported by a ver¬ 
tebral column. [281.] 

Ves'sicle (L. dim. of vesica, a bladder). A little bladder. 

Ves'tibule (L. vestibulum, a tnreshhold). A small oval cavity of the inter* 
nal ear, so named from its forming an entry to the cochlea and semi-circu¬ 
lar canals. [46.] 

Vill'us. Literally, the shaggy hair of beasts. Some of the membranes of 
the body, as the mucous membrane of the intestinal canal, present a sur¬ 
face of minute papillae, termed villi, villosities, resembling a downy tissue, 
continually covered with fluid. 

Vit'reous BoDy (L. vitrum, glass). Vitreous humour. A transparent 
mass, resembling melted glass, occupying the globe of the eye, and inclosed 
in the hyaloid membrane. [376.] 

Voice. [471.] 

W 

Warm-blooded. A term applied to the mammalia and birds which have a 
two-fold circulation. [128.] 

X 

Xyph'oid (Gr. xiphos, a sword, cidos, likeness). Sword-like; a term applied 
to the cartilage of the sternum. 

Z 

Zool'ogy (Gr. zoon, an animal, logos, a description). That branch of Nat¬ 
ural History which treats of animals. 

Zysomat'icus (Gr. zugos, a yoke). A name given to two muscles of the 
face, which are attached to the zygoma or arch formed by the processes of 

the bones. 


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1 Vol. 8vo. 424 Pages. Price $2. 

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III. Compass Surveying.—IV. Transit and Theodolite Surveying.—V. Trigonometri¬ 
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VIII. Plane Table Surveying.—IX. Surveying without Instruments.—X. Mapping.— 
XI. Laying out, Parting Off, aud Dividing up Lands.—XIL United States Public 
Lands. 

Appendix. —A. Synopsis of Plane Trigonometry.—B. Demonstrations of Problems. 
—C. Levelling. 

Tables. —Chords for Platting—Latitudes and Departures—Natural Sines and Cosines. 

Among the leading peculiarities of the work are these ; 

1 . All the operations of surveying are developed from only only jive sim¬ 
ple principles. 

2 . A complete system of surveying with only a chain, a rope, or any sub¬ 
stitute, is fully explained. 

8 . Means of measuring inaccessible distances, in all possible cases, 
with the Chain alone , are triven in great variety, so as to constitute a Land 
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5 . The Traverse Table gives increased accuracy in one fifteenth of the 
space of the usual Tables. 

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vey of old lines, is minutely illustrated. 

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those in common use being in some cases nearly half an hour out of the way. 

8 . The adjustments of the engineer’s Transit and Theodolite are here, for 
the first time', fully developed. 

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with 85 figures. 

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12 The most recent improvements in the methods of surveying the pub¬ 
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Works on Chemistry. 


Chemical Atlas: 


OS; THE CHEMISTRY OF FAMILIAR OBJECTS. 

EXHIBITING TH3 GENERAL PRINCIPLES OF TnE science in a series of beautifully 
COLORED DxAGRAMS, AND ACCOMPANIED BY EXPLANATORY ESSAYS, EMBRACING 
TEE LATEST VIEWS OF TIIE SUBJECIS ILLUSTRATED. DESIGNED FOR THE USE OF 
STUDENTS IN ALL SCHOOLS WHERE CHEMISTRY IS TAUGHT. 

BY EDWARD L. YOUMAYS. 


Large Quarto. 105 pages. Price $2. 


The Atlas is a reproduction (in book form), and a continuation 
of the mode of exhibiting chemical facts and phenomena adopted in 
the author’s “ Chemical Chart.” The application of the diagrams is 
here much extended, occupying thirteen plates, printed in sixteen 
colors, and accompanied by 100 quarto pages of beautifully printed 
explanatory letter-press. It is a chart in a portable and convenient 
form, containing many of the latest views of the science which are 
not found in the text-books. It is designed as an additional aid to 
teachers and pupils, to be used in connection with the author’s 
Class-Book, or as a review, and for individuals who are studying 
alone. 

It is intended to accompany the author’s Class-book of Chemis¬ 
try, but it may be employed with convenience and advantage in 
connection with any of the school text-books on the subject. 


From the TTome Journal. 

Here we have science in pictures—Chemistry in diagrams—eye-dissections of all 
the common forms of matter around us; the chemical composition and properties of 
all familiar objects illustrated to the most impressible of our senses by the aid of colors. 
This is a beautiful book, and as useful as it is beautiful. Mr. Youmans has hit upon 
a happy method of simplifying and bringing out the profoundest abstractions of sci¬ 
ence, so that they fall within the clear comprehension of children. 

From the Utica Morning Herald. 

An excellent idea, well carried out. The style is lucid and happy, the definitions 
concise and clear, and the illustrations felicitous and appropriate. 

From the Lawrence Sentinel. 

"We have devoted some little time in looking over this Atlas, and comparing its 
relative merits with similar treatises heretofore published, and feel bound to accord 
to it the highest degree of approbation and favor. 


From Life illustrated. 

This method of using the eye in education, though not the royal road to know- 
ledge, is really the people s railroad—a means of saying both time and labor. This 
work is worth for actual instruction in common schools far more than a set of appar¬ 
atus, which the teacher might not be able to use, while every one can teach from the 
At as. _We pronounce it, without exception, the best popular work on Chemistry 
in the English language. * 


From the New York Tribune. 

Mr. l oilmans is not a mere routine teacher of his favorite science: he has hit 
upon novel and effective methods for the illustration of its principles. In his writ¬ 
ings, as well as his lectures, he is distinguished for the comprehensive order of his 
his symmetrical arrangement of scientific facts, and the happy manner 
in m hich he addresses the intellect through the medium of ocular demonstration In 
this last respect, his method is both original and singularly ingenious. 



Works on Chemistry, 


Chemical Chart: 

BY E. L. YOUMANS. 

On Rollers, 5 feet by 6 in size. New Edition. Price $5. 

This popular work accomplishes for the first time, for Chemistry, 
what maps and charts have for geography, geology, and astronomy, 
by presenting a new and valuable mode of illustration. Its plan is 
to represent chemical composition to the eye by colored diagrams, 
so that numerous facts of proportion, structure, and relation, 
which are the most difficult in the science, are presented to the 
mind through the medium of the eye, and may thus be easily ac¬ 
quired and long retained. The want of such a chart has long been 
felt by the thoughtful teacher, and no other scientific publication 
that has ever emanated from the American press has met with the 
universal favor that has been accorded to this Chart. In the lan¬ 
guage of a distinguished chemist, “ Its appearance marks an era in 
the progress of the popularization of Chemistry.” 

It illustrates the nature of elements, compounds, affinity, definite 
and multiple proportions, acids, bases, salts, the salt-radical theory, 
double decomposition, deoxidation, combustion and illumination, 
isomerism, compound radicals, and the composition of the proxi¬ 
mate principles of food. It covers the whole field of Agricultural 
Chemistry, and is invaluable as an aid to public lecturers, to teach¬ 
ers in class-room recitation, and for reference in the family. The 
mode of using it is explained in the class-book. 

From the late Horace Mann, President of Antioch College. 

I think Mr. Youmans is entitled to great credit for the preparation of his Chart, 
because its use will not only facilitate acquisition, but, what is of far greater impor¬ 
tance, will increase the exactness and precision of the student's elementary ideas. 

From Dr. John W. Draper, Professor of Chemistry in the University of N. T. 

Mr. Youmans’ Chart seems to me well adapted to communicate to beginners a 
knowledge of the definite combinations of chemical substances, and as a preliminary 
to the use of symbols, to aid them very much in the recollection of the examples it 
contains. It deserves to be introduced into the schools. 

Fron James B. Eogees, Professor of Chemistry in the University of Pennsylvania. 

We cordially subscribe to the opinion of Professor Draper concerning the value 
to beginners of Mr. Youmans’ Chemical Chart. 

JOHN TOEEEY, 

Professor of Chemistry in the College of Physicians & Surgeons, F. Y. 

WM. H. ELLET, 

Late Professor of Chemistry in Columbia College , S. C. 

JAMES B. EOGEES, 

Professor of Chemistry in the University of Pennsylvania. 

From Benjamin Silliman, LL. D., Professor of Chemistry in Yale College. 

I have hastily examined Mr. Youmans’ New Chemical Diagrams or Chart of 
chemical combinations by the union of the elements in atomic proportions. Th® 
design appears to be an excellent one. 




Familiar Science. 


The Hand-Book of Household Science. 

A POPULAR ACCOUNT OF 


Heat, Light, Aik, Aliment, and Cleansing, in their Scientific Principles 
and Domestic Applications. 

BY EDWARD L. YOUMANS. 

12mo. Illustrated. 470 pages. Price $125. 

This work has been prepared to meet a long-acknowledged want 
in our schools. There is a strong and growing demand for that 
kind of knowledge which can be made available in the daily opera¬ 
tions of familiar life. Various books have been prepared which 
cross the field of domestic science at different points, but this is the 
first work that traverses and occupies the whole ground. Hardly 
a page can be opened to that does does not convey information in¬ 
teresting and valuable to every person who dwells in a house. The 
work will be found not only of high practical utility, but captivat¬ 
ing to the student, and unequalled in the interest of its recitations. 

Extract from the Preface. 

“ The purpose has been to condense within the limits of a convenient 
manual the largest possible amount of interesting and valuable scientific 
information of those agents, materials, and operations in which we have a 
concern chiefly as dwellers in houses. 

“ The subjects are treated somewhat in an elementary way, but with 
constant reference to their domestic and practical relations. Principles are 
universal; their applications are special and peculiar. There are general 
laws oflight, heat, and air, but they may be studied in various connections. 
There are many things about them which a person, as a resident of a house, 
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scientific interest to meteorologists; but it has also a special and vital im¬ 
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when brought together, alter and modify each other according to a simple 
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a technical interest in the principle, but hardly more than the lady at her 
toilet, or engaged in furnishing her house. The agriculturist is interested 
in the composition of food as a producer; the householder equally as a con¬ 
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the living system for professional purposes, and he studies these matters as 
parts of liis medical education; but for the same reasons of life and death, 
the inhabitants of houses are concerned to understand the same things. 

“These examples illustrate the leading conception of the present work.” 

4 X 923 

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